MYSQL查询表达方式

查询

SELECT * FROM user;

SELECT user. * FROM user;

查询管理员编号和名称

SELECT id username*FROM user；

表来自哪个数据库下

SELECT id，username FROM user；

字段来自哪张表

SELECT cms_admin.id,cms_admin.username FROM cms.cms_admin;

给表名起别名

SELECT id,username FROM cms_admin AS a;

SELECT a.id,a.username FROM cms.cms_admin AS a;

给字段起别名

SELECT id AS ‘编号’,username AS ‘用户名’ FROM cms_admin;

SELECT a.id AS id1,a.username AS u FROM cmd_admin AS a;

WHERE 条件

查询编号为1的用户

SELECT id,username FROM cms_admin WHERE id=1;

查询编号不为1的用户

SELECT id,username FROM cms_admin WHERE id!=1;

添加age字段

ALTER TABLE cms_admin ADD age TINYINT UNSIGNED DEFAULT 18;

INSERT cms_admin(username,password,age)

VALUES(‘test’,’tes’,NULL);

查询表中记录age值为NULL

SELECT *FROM cms_admin WHERE age<=>NULL;

IS NULL 查询表中记录age值为NULL

SELECT *FROM cms_admin WHERE age IS NULL;

SELECT *FROM cms_admin WHERE age IS NOT NULL;#除了NULL以外的

查询编号3到10之间的用户

SELECT *FROM cms_admin WHERE id BETWEEN 3 AND 10;

查询编号为1,3,5的;( 忽略大小写)

SELECT * FROM cms_admin WHERE id IN(1,3,5);

模糊查询

%: 代表0个一个或者多个任意字符

_:代表1个任意字符

查询姓张的用户

SELECT *FROM cms_admin WHERE username LIKE ‘%张’;

查询用户名中包含in的用户

SELECT *FROM cms_admin WHERE username LIKE ‘%in%’;

查询用户名为3位的用户

SELECT *FROM cms_admin WHERE username LIKE ‘_‘;

用户名_i%

SELECT *FROM csm_admin WHERE username LIKE ‘_I%’;

查询用户名为king并且密码为king的用户名

SELECT *FROM csm_admin WHERE username=’king’ AND password=’king’;

查询编号大于3的变量年龄不为NULL的用户

SELECT *FROM smc_admin WHERE id>3 AND age IS NOT NULL;

查询编号大于3的变量年龄不为NULL 的用户并且proid为3

SELECT *FROM cms_admin WHERE id>3 AND age IS NOT NULL AND proid=3;

查询用户名为以张开始或者用户名所在的身份为2,4的记录

SELECT *FROM cms_admin WHERE username LIKE ‘张%’ OR proid IN(2,4);

按照用户所属的身份分组proid

SELECT *FROM cms_admin GROUP BY proid;

向用户表中添加性别字段

ALTER TABLE csm_admin ADD sex ENUM(‘男’,’女’,’保密’);

UPDATE cms_admin SET sex=’男’ WHERE id IN(1,2,3,4,5);

UPDATE cms_admin SET sex=’男’ WHERE id IN(6,7,8,9,10);

UPDATE cms_admin SET sex=’男’ WHERE id IN(11,12);

按照用户性别分组

SELECT *FROM cms_admin GROUP BY sex;

按照字段位置分组

SELECT *FROM cms_admin GROUP BY 8;#8指的是name的位置

按照多个字段分组

SELECT *FROM cms_admin GROUP BY sex,age;

查询编号大于3的用户按sex分组

SELECT *FROM cms_admin WHERE id>3 GROUP BY sex;

查询详情 ( GROUP_CONCAT(name) )

查询id,sex,用户名详细按照性别分组

SELECT id,sex,GROUP_CONCAT(username) FROM cms_admin GROUP BY sex;

查询prodi,性别详情,注册时间详情,用户名详情,按照proid分组

SELECT proid,GROUP_CONCAT(sex),GROUP_CONCAT(username),GROUP_CONCAT(time) FROM cms_admin GROUP BY proid;

查询编号，sex,用户名详情以及组中总人数按照sex分组

SELECT id,sex,GROUP_CONCAT(username) AS user1 ,COUNT(*) FROM totalUsers csm_admin GROUP BY sex;

统计表中所有记录

SELECT COUNT(*) AS totalusers FROM cms_admin;

COUNT(字段) 不统计NULL值;

SELECT COUNT(age) AS toltalUsers FROM csm_admin;

查询编号,性别,用户名详情,组中总人数,组中最大年龄,最小年龄,平均年龄,以及年龄总和

SELECT id,sex,GROUP_CONCAT(usrname),

COUNT(*) AS totalUsers,

MAX(age) AS max_age,

MIN(age) AS min_age,

AVG(age) AS avg_age,

SUM(age) AS sum_age

FROM cms_user

GROUP BY sex;

WITH ROLLUP 统计MAX,MIN,COUNT,等

SELECT id,sex,GROUP_CONCAT(usrname),

COUNT(*) AS totalUsers,

MAX(age) AS max_age,

MIN(age) AS min_age,

AVG(age) AS avg_age,

SUM(age) AS sum_age

FROM cms_user

GROUP BY sex WITH ROLLUP;

查询性别sex,用户名详情,组中总人数,最大年龄,年龄总和

SELECT sex,GROUP_CONCAT(username) AS users,

COUNT(*) AS totalUsers,

MAX(age) AS max_age,

SUM(age) AS sum_age

FROM coms_admin

GROUP BY sex;

查询组中人数大于2 的

SELECT sex,GROUP_CONCAT(username) AS users,

COUNT(*) AS totalUsers,

MAX(age) AS max_age,

SUM(age) AS sum_age

FROM coms_admin

GROUP BY sex

HAVING COUNT(*)>2;

查询组中人数大于2并且最大年龄大于60的

SELECT sex,GROUP_CONCAT(username) AS users,

COUNT(*) AS totalUsers,

MAX(age) AS max_age,

SUM(age) AS sum_age

FROM coms_admin

GROUP BY sex

HAVING COUNT(*)>2 AND MAX(age)>60;

按照ID降序排列DESC 默认的是ASC

SELECT *FROM cms_admin ORDER BY DESC;

按照年龄升序排列

SELECT *FROM csm_admin ORDER BY age ASC;

SELECT *FROM sma_admin ORDER BY 1 DESC;#1是指name的位置

按照年龄顺序,id降序排列

SELECT *FROM scm_admin ORDER BY age ASC,id DESC;

实现随机记录

SELECT *FROM cms_admin ORDER BY RAND();

查询表中前3条记录

SELECT *FROM csm_admin LIMIT 3;

查询表中的前一条几率

SELECT *FROM cms_admin LIMIT 0,1; #0是起始位置,1第几条