相思资源网

MySQL查询语法汇总
站长资源 2024/11/9 佚名
24 1538
相思资源网 Design By www.200059.com

前言：

本篇文章主要简介下MySQL中where,group by ,order by ,limit,join,union ,union all,子表等查询语法。

测试数据准备

create table emp (  empno numeric(4) not null,  ename varchar(10),  job varchar(9),  mgr numeric(4),  hiredate datetime,  sal numeric(7, 2),  comm numeric(7, 2),  deptno numeric(2));
create table dept (  deptno numeric(2),  dname varchar(14),  loc varchar(13));
create table salgrade (  grade numeric,  losal numeric,  hisal numeric);
insert into dept values (10, 'ACCOUNTING', 'NEW YORK');insert into dept values (20, 'RESEARCH', 'DALLAS');insert into dept values (30, 'SALES', 'CHICAGO');insert into dept values (40, 'OPERATIONS', 'BOSTON');
insert into salgrade values (1, 700, 1200);insert into salgrade values (2, 1201, 1400);insert into salgrade values (3, 1401, 2000);insert into salgrade values (4, 2001, 3000);insert into salgrade values (5, 3001, 9999);
insert into emp values (7369, 'SMITH', 'CLERK', 7902, '1980-12-17', 800, null, 20);insert into emp values (7499, 'ALLEN', 'SALESMAN', 7698, '1981-02-20', 1600, 300, 30);insert into emp values (7521, 'WARD', 'SALESMAN', 7698, '1981-02-22', 1250, 500, 30);insert into emp values (7566, 'JONES', 'MANAGER', 7839, '1981-04-02', 2975, null, 20);insert into emp values (7654, 'MARTIN', 'SALESMAN', 7698, '1981-09-28', 1250, 1400, 30);insert into emp values (7698, 'BLAKE', 'MANAGER', 7839, '1981-05-01', 2850, null, 30);insert into emp values (7782, 'CLARK', 'MANAGER', 7839, '1981-06-09', 2450, null, 10);insert into emp values (7788, 'SCOTT', 'ANALYST', 7566, '1982-12-09', 3000, null, 20);insert into emp values (7839, 'KING', 'PRESIDENT', null, '1981-11-17', 5000, null, 10);insert into emp values (7844, 'TURNER', 'SALESMAN', 7698, '1981-09-08', 1500, 0, 30);insert into emp values (7876, 'ADAMS', 'CLERK', 7788, '1983-01-12', 1100, null, 20);insert into emp values (7900, 'JAMES', 'CLERK', 7698, '1981-12-03', 950, null, 30);insert into emp values (7902, 'FORD', 'ANALYST', 7566, '1981-12-03', 3000, null, 20);insert into emp values (7934, 'MILLER', 'CLERK', 7782, '1982-01-23', 1300, null, 10);

1.模糊查询

mysql> select * from emp where ename like '%S%'; +-------+-------+---------+------+---------------------+---------+------+--------+| empno | ename | job   | mgr | hiredate      | sal   | comm | deptno |+-------+-------+---------+------+---------------------+---------+------+--------+| 7369 | SMITH | CLERK  | 7902 | 1980-12-17 00:00:00 | 800.00 | NULL |   20 || 7566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL |   20 || 7788 | SCOTT | ANALYST | 7566 | 1982-12-09 00:00:00 | 3000.00 | NULL |   20 || 7876 | ADAMS | CLERK  | 7788 | 1983-01-12 00:00:00 | 1100.00 | NULL |   20 || 7900 | JAMES | CLERK  | 7698 | 1981-12-03 00:00:00 | 950.00 | NULL |   30 |+-------+-------+---------+------+---------------------+---------+------+--------+5 rows in set (0.00 sec)
mysql> select * from emp where ename like 'S%'; +-------+-------+---------+------+---------------------+---------+------+--------+| empno | ename | job   | mgr | hiredate      | sal   | comm | deptno |+-------+-------+---------+------+---------------------+---------+------+--------+| 7369 | SMITH | CLERK  | 7902 | 1980-12-17 00:00:00 | 800.00 | NULL |   20 || 7788 | SCOTT | ANALYST | 7566 | 1982-12-09 00:00:00 | 3000.00 | NULL |   20 |+-------+-------+---------+------+---------------------+---------+------+--------+2 rows in set (0.01 sec)
mysql> select * from emp where ename like '%S';+-------+-------+---------+------+---------------------+---------+------+--------+| empno | ename | job   | mgr | hiredate      | sal   | comm | deptno |+-------+-------+---------+------+---------------------+---------+------+--------+| 7566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL |   20 || 7876 | ADAMS | CLERK  | 7788 | 1983-01-12 00:00:00 | 1100.00 | NULL |   20 || 7900 | JAMES | CLERK  | 7698 | 1981-12-03 00:00:00 | 950.00 | NULL |   30 |+-------+-------+---------+------+---------------------+---------+------+--------+3 rows in set (0.00 sec)
mysql> select * from emp where ename like '_O%';+-------+-------+---------+------+---------------------+---------+------+--------+| empno | ename | job   | mgr | hiredate      | sal   | comm | deptno |+-------+-------+---------+------+---------------------+---------+------+--------+| 7566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL |   20 || 7902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000.00 | NULL |   20 |+-------+-------+---------+------+---------------------+---------+------+--------+2 rows in set (0.00 sec)

总结：%表示任意0个或多个字符，可匹配任意类型和长度的字符；_表示任意单个字符，匹配单个任意字符。

2.排序

mysql> select * from emp order by sal;+-------+--------+-----------+------+---------------------+---------+---------+--------+| empno | ename | job    | mgr | hiredate      | sal   | comm  | deptno |+-------+--------+-----------+------+---------------------+---------+---------+--------+| 7369 | SMITH | CLERK   | 7902 | 1980-12-17 00:00:00 | 800.00 |  NULL |   20 || 7900 | JAMES | CLERK   | 7698 | 1981-12-03 00:00:00 | 950.00 |  NULL |   30 || 7876 | ADAMS | CLERK   | 7788 | 1983-01-12 00:00:00 | 1100.00 |  NULL |   20 || 7521 | WARD  | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250.00 | 500.00 |   30 || 7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250.00 | 1400.00 |   30 || 7934 | MILLER | CLERK   | 7782 | 1982-01-23 00:00:00 | 1300.00 |  NULL |   10 || 7844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500.00 |  0.00 |   30 || 7499 | ALLEN | SALESMAN | 7698 | 1981-02-20 00:00:00 | 1600.00 | 300.00 |   30 || 7782 | CLARK | MANAGER  | 7839 | 1981-06-09 00:00:00 | 2450.00 |  NULL |   10 || 7698 | BLAKE | MANAGER  | 7839 | 1981-05-01 00:00:00 | 2850.00 |  NULL |   30 || 7566 | JONES | MANAGER  | 7839 | 1981-04-02 00:00:00 | 2975.00 |  NULL |   20 || 7788 | SCOTT | ANALYST  | 7566 | 1982-12-09 00:00:00 | 3000.00 |  NULL |   20 || 7902 | FORD  | ANALYST  | 7566 | 1981-12-03 00:00:00 | 3000.00 |  NULL |   20 || 7839 | KING  | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 |  NULL |   10 |+-------+--------+-----------+------+---------------------+---------+---------+--------+14 rows in set (0.00 sec)
mysql> select * from emp order by sal asc;+-------+--------+-----------+------+---------------------+---------+---------+--------+| empno | ename | job    | mgr | hiredate      | sal   | comm  | deptno |+-------+--------+-----------+------+---------------------+---------+---------+--------+| 7369 | SMITH | CLERK   | 7902 | 1980-12-17 00:00:00 | 800.00 |  NULL |   20 || 7900 | JAMES | CLERK   | 7698 | 1981-12-03 00:00:00 | 950.00 |  NULL |   30 || 7876 | ADAMS | CLERK   | 7788 | 1983-01-12 00:00:00 | 1100.00 |  NULL |   20 || 7521 | WARD  | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250.00 | 500.00 |   30 || 7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250.00 | 1400.00 |   30 || 7934 | MILLER | CLERK   | 7782 | 1982-01-23 00:00:00 | 1300.00 |  NULL |   10 || 7844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500.00 |  0.00 |   30 || 7499 | ALLEN | SALESMAN | 7698 | 1981-02-20 00:00:00 | 1600.00 | 300.00 |   30 || 7782 | CLARK | MANAGER  | 7839 | 1981-06-09 00:00:00 | 2450.00 |  NULL |   10 || 7698 | BLAKE | MANAGER  | 7839 | 1981-05-01 00:00:00 | 2850.00 |  NULL |   30 || 7566 | JONES | MANAGER  | 7839 | 1981-04-02 00:00:00 | 2975.00 |  NULL |   20 || 7788 | SCOTT | ANALYST  | 7566 | 1982-12-09 00:00:00 | 3000.00 |  NULL |   20 || 7902 | FORD  | ANALYST  | 7566 | 1981-12-03 00:00:00 | 3000.00 |  NULL |   20 || 7839 | KING  | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 |  NULL |   10 |+-------+--------+-----------+------+---------------------+---------+---------+--------+14 rows in set (0.00 sec)
mysql> select * from emp order by sal desc;+-------+--------+-----------+------+---------------------+---------+---------+--------+| empno | ename | job    | mgr | hiredate      | sal   | comm  | deptno |+-------+--------+-----------+------+---------------------+---------+---------+--------+| 7839 | KING  | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 |  NULL |   10 || 7788 | SCOTT | ANALYST  | 7566 | 1982-12-09 00:00:00 | 3000.00 |  NULL |   20 || 7902 | FORD  | ANALYST  | 7566 | 1981-12-03 00:00:00 | 3000.00 |  NULL |   20 || 7566 | JONES | MANAGER  | 7839 | 1981-04-02 00:00:00 | 2975.00 |  NULL |   20 || 7698 | BLAKE | MANAGER  | 7839 | 1981-05-01 00:00:00 | 2850.00 |  NULL |   30 || 7782 | CLARK | MANAGER  | 7839 | 1981-06-09 00:00:00 | 2450.00 |  NULL |   10 || 7499 | ALLEN | SALESMAN | 7698 | 1981-02-20 00:00:00 | 1600.00 | 300.00 |   30 || 7844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500.00 |  0.00 |   30 || 7934 | MILLER | CLERK   | 7782 | 1982-01-23 00:00:00 | 1300.00 |  NULL |   10 || 7521 | WARD  | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250.00 | 500.00 |   30 || 7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250.00 | 1400.00 |   30 || 7876 | ADAMS | CLERK   | 7788 | 1983-01-12 00:00:00 | 1100.00 |  NULL |   20 || 7900 | JAMES | CLERK   | 7698 | 1981-12-03 00:00:00 | 950.00 |  NULL |   30 || 7369 | SMITH | CLERK   | 7902 | 1980-12-17 00:00:00 | 800.00 |  NULL |   20 |+-------+--------+-----------+------+---------------------+---------+---------+--------+14 rows in set (0.00 sec)

总结：order by排序默认按asc升序来排列也可指定desc降序排列

3.限制多少行

mysql> select * from emp limit 3;+-------+-------+----------+------+---------------------+---------+--------+--------+| empno | ename | job   | mgr | hiredate      | sal   | comm  | deptno |+-------+-------+----------+------+---------------------+---------+--------+--------+| 7369 | SMITH | CLERK  | 7902 | 1980-12-17 00:00:00 | 800.00 |  NULL |   20 || 7499 | ALLEN | SALESMAN | 7698 | 1981-02-20 00:00:00 | 1600.00 | 300.00 |   30 || 7521 | WARD | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250.00 | 500.00 |   30 |+-------+-------+----------+------+---------------------+---------+--------+--------+3 rows in set (0.00 sec)
mysql> select * from emp order by sal desc limit 3;+-------+-------+-----------+------+---------------------+---------+------+--------+| empno | ename | job    | mgr | hiredate      | sal   | comm | deptno |+-------+-------+-----------+------+---------------------+---------+------+--------+| 7839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 | NULL |   10 || 7902 | FORD | ANALYST  | 7566 | 1981-12-03 00:00:00 | 3000.00 | NULL |   20 || 7788 | SCOTT | ANALYST  | 7566 | 1982-12-09 00:00:00 | 3000.00 | NULL |   20 |+-------+-------+-----------+------+---------------------+---------+------+--------+3 rows in set (0.00 sec)

总结：limit限定显示前多少行，可与order by联合使用

4.聚合函

count() sum()函数用法：#1.各个部门的薪水和mysql> select deptno,sum(sal) from emp group by deptno;+--------+----------+| deptno | sum(sal) |+--------+----------+|   10 | 8750.00 ||   20 | 10875.00 ||   30 | 9400.00 |+--------+----------+3 rows in set (0.01 sec)
#2.group by字段必须出现在select字段后面  各个部门的各个岗位的薪水和mysql> select deptno,job, sum(sal) from emp group by deptno ,job;+--------+-----------+----------+| deptno | job    | sum(sal) |+--------+-----------+----------+|   10 | CLERK   | 1300.00 ||   10 | MANAGER  | 2450.00 ||   10 | PRESIDENT | 5000.00 ||   20 | ANALYST  | 6000.00 ||   20 | CLERK   | 1900.00 ||   20 | MANAGER  | 2975.00 ||   30 | CLERK   |  950.00 ||   30 | MANAGER  | 2850.00 ||   30 | SALESMAN | 5600.00 |+--------+-----------+----------+9 rows in set (0.01 sec)
#3.having  薪水和>5000的各个部门的各个岗位mysql> select deptno,job, sum(sal)   -> from emp   -> group by deptno ,job  -> having sum(sal)>5000; +--------+----------+----------+| deptno | job   | sum(sal) |+--------+----------+----------+|   20 | ANALYST | 6000.00 ||   30 | SALESMAN | 5600.00 |+--------+----------+----------+2 rows in set (0.00 sec)#4.常用组合where order limit select deptno,job, sum(sal) as sum_salfrom emp where job='SALESMAN'group by deptno ,jobhaving sum(sal)>5000 order by sum(sal) desc limit 1;

下面介绍下join及union的用法
数据准备：

create table testa(aid int,aname varchar(40));
create table testb(bid int,bname varchar(40),age int);
insert into testa values(1,'xiaoming');insert into testa values(2,'LY');insert into testa values(3,'KUN');insert into testa values(4,'ZIDONG');insert into testa values(5,'HB');

insert into testb values(1,'xiaoming',10);insert into testb values(2,'LY',100);insert into testb values(3,'KUN',200);insert into testb values(4,'ZIDONG',110);insert into testb values(6,'niu',120);insert into testb values(7,'meng',130);insert into testb values(8,'mi',170);

5.left join

mysql> select  -> a.aid,a.aname,  -> b.bid,b.bname,b.age  -> from testa as a  -> left join testb as b on a.aid=b.bid; +------+----------+------+----------+------+| aid | aname  | bid | bname  | age |+------+----------+------+----------+------+|  1 | xiaoming |  1 | xiaoming |  10 ||  2 | LY    |  2 | LY    | 100 ||  3 | KUN   |  3 | KUN   | 200 ||  4 | ZIDONG  |  4 | ZIDONG  | 110 ||  5 | HB    | NULL | NULL   | NULL |+------+----------+------+----------+------+5 rows in set (0.00 sec)

总结：a left join b  a表全，用b表去匹配a表LEFT JOIN 关键字会从左表 (a) 那里返回所有的行，即使在右表 (b) 中没有匹配的行,匹配不到的列用NULL代替

6.right join

mysql> select  -> a.aid,a.aname,  -> b.bid,b.bname,b.age  -> from testa as a  -> right join testb as b on a.aid=b.bid;+------+----------+------+----------+------+| aid | aname  | bid | bname  | age |+------+----------+------+----------+------+|  1 | xiaoming |  1 | xiaoming |  10 ||  2 | LY    |  2 | LY    | 100 ||  3 | KUN   |  3 | KUN   | 200 ||  4 | ZIDONG  |  4 | ZIDONG  | 110 || NULL | NULL   |  6 | niu   | 120 || NULL | NULL   |  7 | meng   | 130 || NULL | NULL   |  8 | mi    | 170 |+------+----------+------+----------+------+7 rows in set (0.00 sec)

总结：a right join b  b表全，用a表去匹配b表RIGHT JOIN 关键字会右表 (b) 那里返回所有的行，即使在左表 (a) 中没有匹配的行,匹配不到的列用NULL代替

7.inner join

mysql> select  -> a.aid,a.aname,  -> b.bid,b.bname,b.age  -> from testa as a  -> inner join testb as b on a.aid=b.bid; +------+----------+------+----------+------+| aid | aname  | bid | bname  | age |+------+----------+------+----------+------+|  1 | xiaoming |  1 | xiaoming |  10 ||  2 | LY    |  2 | LY    | 100 ||  3 | KUN   |  3 | KUN   | 200 ||  4 | ZIDONG  |  4 | ZIDONG  | 110 |+------+----------+------+----------+------+4 rows in set (0.00 sec)
mysql> select  -> a.aid,a.aname,  -> b.bid,b.bname,b.age  -> from testa as a  -> join testb as b on a.aid=b.bid; +------+----------+------+----------+------+| aid | aname  | bid | bname  | age |+------+----------+------+----------+------+|  1 | xiaoming |  1 | xiaoming |  10 ||  2 | LY    |  2 | LY    | 100 ||  3 | KUN   |  3 | KUN   | 200 ||  4 | ZIDONG  |  4 | ZIDONG  | 110 |+------+----------+------+----------+------+4 rows in set (0.00 sec)

总结：inner join 与join 效果一样在表中存在至少一个匹配时，INNER JOIN 关键字返回行

8.union与union all

mysql> select aid,aname from testa  -> union  -> select bid,bname from testb;+------+----------+| aid | aname  |+------+----------+|  1 | xiaoming ||  2 | LY    ||  3 | KUN   ||  4 | ZIDONG  ||  5 | HB    ||  6 | niu   ||  7 | meng   ||  8 | mi    |+------+----------+8 rows in set (0.01 sec)
mysql> select aid,aname from testa  -> union all  -> select bid,bname from testb;+------+----------+| aid | aname  |+------+----------+|  1 | xiaoming ||  2 | LY    ||  3 | KUN   ||  4 | ZIDONG  ||  5 | HB    ||  1 | xiaoming ||  2 | LY    ||  3 | KUN   ||  4 | ZIDONG  ||  6 | niu   ||  7 | meng   ||  8 | mi    |+------+----------+12 rows in set (0.00 sec)

总结：union 会去重 union all不去重

以上就是MySQL查询语法汇总的详细内容，更多关于MySQL查询语法的资料请关注其它相关文章！

标签：
MySQL,查询,MySQL,查询语法
相思资源网 Design By www.200059.com
广告合作：本站广告合作请联系QQ：858582 申请时备注：广告合作（否则不回）
免责声明：本站文章均来自网站采集或用户投稿，网站不提供任何软件下载或自行开发的软件！ 如有用户或公司发现本站内容信息存在侵权行为，请邮件告知！ 858582#qq.com
相思资源网 Design By www.200059.com

评论“MySQL查询语法汇总”

暂无MySQL查询语法汇总的评论...
www.200059.com 相思资源网
139,976影音资源
144,792福利资源
21,817软件资源
631,128技术资源
一句话新闻
苹果官宣WWDC 2024！预计会有大批AI功能 - 2024/11/9

3月27日消息，苹果宣布2024年全球开发者大会（WWDC）将于6月10日至6月14日举行，巧合的是，这次大会与端午假期重合。

苹果官方表示：

在线参加 Apple 每年规模最大的开发者盛会。亲眼见证 Apple 最新平台、技术和工具的发布。了解如何创建和改进你的 App 和游戏。与 Apple 设计师和工程师互动交流，与全球开发者社区建立联系。以上活动均免费在线举行。

探索各种新的工具、框架和功能，助力你打造出理想的 App 和游戏。通过视频讲座学习新技能，与 Apple 专家进行一对一会面，以推进你的项目，完善你的构思。

Swift Student Challenge 旨在支持和鼓舞下一代开发者、创作者和企业家。太平洋时间 3 月 28 日，我们将公布今年的获奖者名单。获奖者将有资格参加在 Apple Park 举办的特别活动。我们还会选出 50 名杰出获胜者，他们将受邀前往库比提诺，获得为期三天的非凡体验，包括参加 Apple Park 的特别活动。

RTX 5090要首发 性能要翻倍！三星展示GDDR7显存

三星在GTC上展示了专为下一代游戏GPU设计的GDDR7内存。

首次推出的GDDR7内存模块密度为16GB，每个模块容量为2GB。其速度预设为32 Gbps（PAM3），但也可以降至28 Gbps，以提高产量和初始阶段的整体性能和成本效益。

据三星表示，GDDR7内存的能效将提高20%，同时工作电压仅为1.1V，低于标准的1.2V。通过采用更新的封装材料和优化的电路设计，使得在高速运行时的发热量降低，GDDR7的热阻比GDDR6降低了70%。

友情链接

杰晶网络 DDR爱好者之家 桃源资源网 杰网资源 富贵资源网 南强小屋 铁雪资源网 幽灵资源网 万梅资源网 狼山资源网 白云岛资源网 昆仑资源网 相思资源网 明霞山资源网 内蒙古资源网 黑松山资源网 茶园资源网 饿虎岗资源网 大旗谷资源网 常春岛资源网 岱庙资源网 兴国资源网 快活林资源网 蝙蝠岛资源网 帝王谷资源网 白云城资源网 伏龙阁资源网 清风细雨楼 天枫庄资源网 圆月山庄资源网 无争山庄资源网 神水资源网 移花宫资源网 神剑山庄资源网 无为清净楼资源网 金钱帮资源网 丐帮资源网 华山资源网 极乐门资源网 小李飞刀资源网 凤求凰客栈 风云阁资源网 金狮镖局 鸳鸯亭资源网 千金楼资源网 更多链接
相思资源网 Design By www.200059.com