SQL学习笔记--创建表、约束、修改表

<code class="hljs sql has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--复制表</span>
<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">CREATE</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">TABLE</span> MYEMP <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">AS</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">SELECT</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FROM</span> EMP;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>

<code class="hljs sql has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--insert操作</span>
语法：<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">insert</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">into</span> 表名(字段<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>,字段<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2.</span>...) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">values</span> (值<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>,值<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2.</span>...)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">INSERT</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">INTO</span> MYEMP (empno,ename,job,mgr,hiredate,sal,comm,deptno)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">VALUES</span> (<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">9527</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'唐伯虎'</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'SALESMAN'</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">7839</span>,sysdate,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2500</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">130</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">40</span>);</span>

<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">INSERT</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">INTO</span> MYEMP (empno,ename,job,sal,comm,deptno)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">VALUES</span> (<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1521</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'wow'</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'CLERK'</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1600</span>,<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>);</span>

<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">INSERT</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">INTO</span> MYEMP <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">VALUES</span> (<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3306</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'lol'</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'PERSIDENT'</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">7788</span>,to_date(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'2008-2-14'</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'yyyy-mm-dd'</span>),<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1000</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">30</span>);</span>

<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">SELECT</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FROM</span> MYEMP;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li></ul>

<code class="hljs sql has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--delete操作</span>
语法：<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">delete</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">from</span> 表名 <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">where</span> 条件
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">DELETE</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FROM</span> MYEMP <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">WHERE</span> EMPNO=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">9257</span>;</span>

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">------截断表truncate;截断表功能上类似于没有where子句的delete</span>
语法：<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">truncate</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">table</span> 表名;</span>

<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">truncate</span>与<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">delete</span>的区别：
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">delete</span>会记录日志，所以速度较慢；而<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">truncate</span>不会记录日志，清空表并释放表所占的资源，所以速度快
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">delete</span>可以根据条件只删除部门数据，而<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">truncate</span>只能一次清空表中所有数据
</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li></ul>

<code class="hljs sql has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--update操作</span>
语法：<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">update</span> 表名 <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span> 字段<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>=值<span class="hlj
15f5f
s-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>,字段<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>=值<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2.</span>.. <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">where</span> 条件
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">UPDATE</span> MYEMP <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">SET</span> SAL=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">888</span>,COMM=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">222</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">WHERE</span> ENAME=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'LOL'</span>;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>

<code class="hljs sql has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--创建表</span>
<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">create</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">table</span> 表名（字段名 类型 [<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">default</span> 默认的值]，字段名 类型[<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">default</span> 默认的值]，...)

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">create</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">table</span> 表名 <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">as</span>（<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">select</span>语句）
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">select</span>语句：<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">select</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">from</span> 表名<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>：复制一张表，和<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">select</span> 表中的结构和数据一样
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">select</span>语句：<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">select</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">from</span> 表名<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">where</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>:复制一张表，和<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">select</span> 表中的结构一样

创建一张person表（身份证号pid，姓名name，生日bithday，性别sex 默认性别是男）
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">CREATE</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">TABLE</span> PERSON
(
PID <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">NUMBER</span> (<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">20</span>),
NAME VARCHAR2(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>),
BIRTHDAY <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">DATE</span>,
SEX VARCHAR2(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">DEFAULT</span> <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'男'</span>
);</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li></ul>

<code class="hljs sql has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--创建表并添加约束</span>
<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">CREATE</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">TABLE</span> goods(
goodsid varchar2(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">8</span>),
goodname varchar2(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">20</span>),
unitprice <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">number</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>),
category varchar2(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">8</span>),
provider varchar2(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">30</span>),
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">CONSTRAINT</span> goodsid_pk <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">PRIMARY</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">KEY</span>(goodsid),--添加主键约束
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">CONSTRAINT</span> unitprice_ck <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">check</span>(unitprice><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>) --添加检查约束

);</span>

<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">CREATE</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">TABLE</span> customer(
customerid varchar2(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>),
name varchar2(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">8</span>) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">NOT</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">NULL</span>,      --添加非空约束
address varchar2(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">20</span>),
email <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">number</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>),
sex varchar2(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">8</span>),
cardid varchar2(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">30</span>),
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">CONSTRAINT</span> customerid_pk <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">PRIMARY</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">KEY</span>(customerid),
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">CONSTRAINT</span> email_uq <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">unique</span>(email),      --添加唯一约束
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">CONSTRAINT</span> sex_ck <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">check</span>(sex <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">in</span> (<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'male'</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'female'</span>))
);</span>

<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">CREATE</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">TABLE</span> purchase(
customerid varchar2(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">8</span>),
goodsid varchar2(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">8</span>),
nums <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">number</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>),
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">CONSTRAINT</span> customer_fk <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FOREIGN</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">KEY</span>(customerid) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">REFERENCES</span> customer_wzl(customerid),
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">CONSTRAINT</span> goods_fk <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FOREIGN</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">KEY</span>(goodsid) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">REFERENCES</span> goods_wzl1(goodsid),   --添加外键约束
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">CONSTRAINT</span> nums_ck <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">check</span>(nums between <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">and</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">30</span>)
);</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li></ul>

<code class="hljs sql has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--修改表</span>
添加列：<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">alter</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">table</span> 表名  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">add</span>(字段名 类型 [<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">default</span> 默认的值]，字段名 类型[<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">default</span> 默认的值]，...);</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">---为person增加一个字段（address）</span>
<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">alter</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">table</span> person <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">add</span>(address varchar2(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">50</span>));</span>

修改列的类型和默认值：<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">alter</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">table</span> 表名 modify(字段名 类型 [<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">default</span> 默认的值]，字段名 类型[<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">default</span> 默认的值]，...);</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">---修改person字段sex的默认值为女：</span>
<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">alter</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">table</span> person modify(sex varchar2(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">default</span> <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'女'</span>);</span>

字段重命名：<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">alter</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">table</span> 表名 rename <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">column</span> 旧的字段名 <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">to</span> 新的字段名;</span>

为表重命令:<span class="hljs-operator" style="box-sizing: border-box;">rename 旧的表名 <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">to</span> 新的表名
删除列：<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">alter</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">table</span> 表名  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">drop</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">column</span> 字段名;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li></ul>

<code class="hljs sql has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--删除表</span>
<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">drop</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">table</span> 表名;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>

<code class="hljs applescript has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--添加注释</span>
可以为表或字段添加注释
comment <span class="hljs-function_start" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">on</span></span> table 表名 <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">is</span> 注释;
comment <span class="hljs-function_start" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">on</span></span> column 表名.列名 <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">is</span> 注释;

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">---给表a添加注释</span>
SQL>comment <span class="hljs-function_start" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">on</span></span> table a <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">is</span> 'test table';

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">---查看表a的注释</span>
SQL>select * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">from</span> user_tab_comments <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">where</span> table_name='A';

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">---给表a中列birthday添加注释</span>
SQL>comment <span class="hljs-function_start" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">on</span></span> column a.birthday <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">is</span> '出生日期';

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">---查看字段的注释</span>
SQL>select * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">from</span> user_col_comments <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">where</span> table_name='A';</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li></ul>

<code class="hljs sql has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--行号、物理地址</span>
7)ROWNUM 行号，伪列
<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">SELECT</span> ROWNUM,DEPTNO,DNAME <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FROM</span> DEPT;</span> <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--行号，伪列</span>

查询出emp表的前5条记录
<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">SELECT</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FROM</span> EMP <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">WHERE</span> ROWNUM<=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>;</span>

查询出emp表的第6条到第9条的记录   <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--ROWNUM没有>,>=的用法</span>

<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">SELECT</span> TEMP.RM,TEMP.EMPNO,TEMP.ENAME
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FROM</span> (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">SELECT</span> ROWNUM RM,EMPNO,ENAME <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FROM</span> EMP) TEMP
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">WHERE</span> TEMP.RM BETWEEN <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">AND</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">9</span>;</span>

ROWID 物理地址     <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--ROWID 物理地址  ,主要用于删除表中大量重复的记录</span>
<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">SELECT</span> ROWID ,DEPT.* <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FROM</span> DEPT;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li></ul>

<code class="hljs sql has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--集合操作</span>
UNION: 并
<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">SELECT</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FROM</span> EMP <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">UNION</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">SELECT</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FROM</span> EMP <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">WHERE</span> DEPTNO=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>;</span>

UNION ALL:并，不去除重复记录
<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">SELECT</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FROM</span> EMP <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">UNION</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">ALL</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">SELECT</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FROM</span> EMP <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">WHERE</span> DEPTNO=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>;</span>

MINUS:取2个查询结果中不同的部分
<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">SELECT</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FROM</span> EMP MINUS <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">SELECT</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FROM</span> EMP <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">WHERE</span> DEPTNO=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>;</span>

INTERSECT: 交叉
<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">SELECT</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FROM</span> EMP <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">INTERSECT</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">SELECT</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">FROM</span> EMP <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">WHERE</span> DEPTNO=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>

<code class="hljs sql has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--事务操作</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--事务处理：用来保证数据的完整性，事务中所有的操作要么都成功，要么都失败</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--事务特性：原子性、一致性、永久性、隔离性</span>
在Oracle中每打开一个窗口，都会与数据库建立一个会话Session，一个Session对数据库所做的修改，不会立即更新到数据库中，而是只在在缓冲区中，允许回滚操作

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--事务操作</span>
<span class="hljs-operator" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">commit</span> 提交事务
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">rollback</span> 回滚事务

事务保存点
可以把一个事务分成多个部分
设置回滚点：
savepoint  事务保存点
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">rollback</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">to</span> 事务保存点

注：一旦提交了事务，则肯定无法回滚
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">commit</span>操作被内置在DDL语句中，即执行DDL操作时会自动提交事务</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li></ul>

<code class="hljs livecodeserver has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--表的管理</span>
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>）基本数据类型
字符型：
varchar2(n):实际占用多少就多少
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span>(n):如果不足，是以空格来填充

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>):<span class="hljs-operator" style="box-sizing: border-box;">a</span>

数值型
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">number</span>(p,s)
s=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">number</span>(p,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>)=<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">number</span>(p):整数
s><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>:小数的右边S位
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">number</span>(p点,s)
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4566.45</span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">number</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>)
s<<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>:小数点左边S位

日期型
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">date</span>表示日期，默认格式为：<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">31</span>-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>月-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">14</span>

larger object(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4</span>G)
clob 大文本数据
blob 二进制大数据</code>