oracle常用函数集锦

数值函数

SELECT Distinct ABS(-5) FROM emp;

SELECT * FROM dual;

SELECT ABS(-5) FROM dual;

SELECT CEIL(5.8) FROM dual;

SELECT FLOOR(5.8) FROM dual;

SELECT ROUND(5.8) FROM dual;

SELECT ROUND(5.3) FROM dual;

SELECT TRUNC(5.3) FROM dual;

SELECT TRUNC(5.8) FROM dual;

--查询员工的姓名,日工资(精确地小数点后2位)

SELECT ename,trunc(sal/21,2) FROM emp;

SELECT ename,ROUND(sal/21,2) FROM emp;

字符串函数

SELECT CONCAT('this is',' test') FROM dual;

SELECT 'this is'||' test' FROM dual;

SELECT ename||'属于'||d.dname AS 员工信息 FROM emp e,dept d WHERE e.deptno=d.deptno;

SELECT ename||'属于'||d.dname 员工信息 FROM emp e,dept d WHERE e.deptno=d.deptno;

SELECT Instr('AAAAABCCAB','B') FROM dual;--下标从1开始

SELECT Instr('AAAAABCCABcB','BC',7,1) FROM dual;

SELECT Instr('AAAAABCCABcB','B',7,2) FROM dual;

SELECT Instr('AAAAABCCABcB','BC',7,1) FROM dual;

SELECT Instr('AAAAABCCABcB','BC') FROM dual;

SELECT LOWER('AAAAABCCABcB') FROM dual;

SELECT UPPER('This is Abc') FROM dual;

SELECT nls_initcap('this is abc') FROM dual;

SELECT LPAD('this',10,'*') FROM dual;

SELECT RPAD('this',10,'*') FROM dual;

SELECT '*'||TRIM(' this is test ')||'*' FROM dual;

SELECT '*'||LTRIM(' this is test ')||'*' FROM dual;

SELECT '*'||RTRIM(' this is test ')||'*' FROM dual;

SELECT LTRIM('!*!*this is test!*!*','!*') FROM dual;

SELECT RTRIM('!*!*this is test!*!*','!*') FROM dual;

SELECT TRIM('!' FROM '!!!!*!*this is test!*!*!!!!') FROM dual;

SELECT substr('this is a test',6,2) FROM dual;

--从身份证号中截取出生日期,显示格式yyyy年mm月dd日

SELECT REPLACE('this is a string','is','was') from dual;

SELECT REPLACE('this is a string','is') from dual;

日期函数

SELECT SYSDATE FROM dual;--获取系统当前时间

SELECT add_months(SYSDATE,1) FROM dual;

SELECT add_months('6-5月-2014',1) FROM dual;

SELECT add_months('28-2月-2014',1) FROM dual;

SELECT hiredate,add_months(hiredate,10*12) AS "10年后" FROM emp;

SELECT ename,EXTRACT(YEAR FROM hiredate) 入职年份 FROM emp;

SELECT ename,ceil(months_between(SYSDATE,hiredate)/12) 入职时长 FROM emp;

SELECT next_day(SYSDATE,'星期三') FROM dual;

SELECT next_day(SYSDATE,'星期六') FROM dual;

SELECT current_date FROM dual;

--获取系统当前时间，并以2000年3月5日 12:10:10格式显示

类型转换函数

SELECT EXTRACT(YEAR FROM SYSDATE)||'年'||EXTRACT(MONTH FROM SYSDATE)||'月'||EXTRACT(DAY FROM SYSDATE)||'日' FROM dual;

SELECT to_char(SYSDATE,'yyyy-MM-dd hh:mm:ss') FROM dual;

SELECT to_char(123.45)||'1' FROM dual;

SELECT to_char(123.45)+1 FROM dual;

SELECT to_char(1234567.89,'$999,999,999.99') from dual;

SELECT to_char(1234567.89,'L999,999,999.99') from dual;

SELECT to_date('03-4月-82')from dual;

SELECT to_date('18-4-2012','dd-mm-yyyy') from dual;

SELECT to_date('2012-4-18','yyyy-mm-dd') from dual;

SELECT to_date('2012-4-18 8:50:3','yyyy-MM-dd hh:mi:ss') from dual;

SELECT * FROM emp WHERE hiredate>to_date('1982-1-1','yyyy-mm-dd');

SELECT to_number('123.45')+2 FROM dual;

SELECT to_number(' ￥1,234,567.89','L999,999,999.99')+2 FROM dual;

SELECT to_number(' $1,234,567.89','$999,999,999.99')+2 FROM dual;

其他函数

SELECT ename, DECODE(deptno,10,'ACCOUNTING',20,'RESEARCH',30,'SALES',40,'OPERATIONS','others') FROM emp

SELECT ename,comm,NVL(comm,-1) NVL FROM emp;

SELECT COUNT(*) FROM emp;

SELECT COUNT(1) FROM emp;

SELECT COUNT(DISTINCT job) FROM emp;

SELECT AVG(sal) 平均工资,SUM(sal) 总工资 FROM emp;

SELECT MAX(sal) 最高工资,MIN(sal) 最低工资 FROM emp;

--统计基本工资超过1000的员工中,每个工种的工人数量,并且将工人数量大于等于3的信息打印出来

SELECT job,COUNT(*) 数量 FROM emp WHERE sal>1000 GROUP BY job HAVING COUNT(*)>=3 ORDER BY 数量 ASC;

SELECT job,COUNT(*) FROM emp GROUP BY job HAVING COUNT(*)>=3 ;

--where:对分组之前基本数据进行条件筛选

--having:对分组之后的结果进行条件筛选,有having必须要有group by