MySQL基础代码示例

• 向emp表中插入数据

  `INSERT INTO emp(id,NAME,gender,birthday,salary,entry_date,RESUME) VALUE (1,'Tom','m','2005-1-1',10000,'2016-10-29','good boy')

INSERT INTO emp(id,NAME,gender,birthday,salary,entry_date,RESUME) VALUE (2,'Alice','f','2005-1-1',10000,'2016-10-29','good girl')`

• 将所有员工薪水修改为5000元

  UPDATE emp SET salary = 50000

• 将姓名为’Tom’的员工薪水修改为3000元。

  UPDATE emp SET salary = 3000 WHERE NAME = 'Tom'

• 将姓名为’Alice’的员工薪水修改为4000元,性别改为m

  UPDATE emp SET salary = 4000,gender = 'm' WHERE NAME = 'Alice'

• 将Alice的薪水在原有基础上增加1000元。

  UPDATE emp SET salary = salary+1000 WHERE NAME = 'Alice'

• 删除表中名称为’Tom’的记录。

  DELETE FROM emp WHERE NAME = 'Tom'

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• 创建学生表

  CREATE TABLE stu( sid VARCHAR(6), sname VARCHAR(50), age INT, gender VARCHAR(20) )

• 向学生表插入一些数据

  INSERT INTO stu VALUES('S_1001', 'liuYi', 35, 'male'); INSERT INTO stu VALUES('S_1002', 'chenEr', 15, 'female'); INSERT INTO stu VALUES('S_1003', 'zhangSan', 95, 'male'); INSERT INTO stu VALUES('S_1004', 'liSi', 65, 'female'); INSERT INTO stu VALUES('S_1005', 'wangWu', 55, 'male'); INSERT INTO stu VALUES('S_1006', 'zhaoLiu', 75, 'female'); INSERT INTO stu VALUES('S_1007', 'sunQi', 25, 'male'); INSERT INTO stu VALUES('S_1008', 'zhouBa', 45, 'female'); INSERT INTO stu VALUES('S_1009', 'wuJiu', 85, 'male'); INSERT INTO stu VALUES('S_1010', 'zhengShi', 5, 'female'); INSERT INTO stu VALUES('S_1011', 'xxx', NULL, NULL);

• 删除emp表

  DROP TABLE emp

• 创建雇员表并插入数据

  CREATE TABLE emp( empno INT, ename VARCHAR(50), job VARCHAR(50), mgr INT, hiredate DATE, sal DECIMAL(7,2), comm DECIMAL(7,2), deptno INT ) 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,'1987-04-19',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,'1987-05-23',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);

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• 查询指定列

  SELECT sid FROM stu

• 查询性别为女，并且年龄50的记录

  SELECT * FROM stu WHERE gender = 'female' AND age >50

• 查询学号为S_1001，或者姓名为liSi的记录

  SELECT * FROM stu WHERE sid = 's_1001' OR sname = 'lisi'

• 查询学号为S_1001，S_1002，S_1003的记录

  SELECT * FROM stu WHERE sid IN('S_1001','S_1002','S_1003')

• 查询学号不是S_1001，S_1002，S_1003的记录

  SELECT * FROM stu WHERE sid NOT IN('S_1001','S_1002','S_1003')

• 查询年龄为null的记录

  SELECT * FROM stu WHERE age IS NULL

• 查询年龄在20到40之间的学生记录

  SELECT * FROM stu WHERE age BETWEEN 20 AND 40

• 查询性别非男的学生记录

  SELECT * FROM stu WHERE gender ='female'

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• 模糊查询*

• 查询姓名由5个字母构成的学生记录

  SELECT * FROM stu WHERE sname LIKE '_____'

• 查询姓名由5个字母构成，并且第5个字母为“i”的学生记录

  SELECT * FROM stu WHERE sname LIKE '____i'

• 查询姓名以“z”开头的学生记录

  SELECT * FROM stu WHERE sname LIKE 'z%'

• 查询姓名中第2个字母为“i”的学生记录

  SELECT * FROM stu WHERE sname LIKE '_i%'

• 查询姓名中包含“a”字母的学生记录

  SELECT * FROM stu WHERE sname LIKE '%a%'

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• 字段控制查询

• 去除重复记录

  SELECT DISTINCT deptno FROM emp

• 查看雇员的月薪与佣金之和

  SELECT sal+IFNULL(comm,0) FROM emp

• 给列名添加别名

  SELECT sal+IFNULL(comm,0) AS total FROM emp

• 排序 order by 列名 asc(默认) desc

  SELECT * FROM stu ORDER BY age

• 查询所有雇员，按月薪降序排序，如果月薪相同时，按编号升序排序

  SELECT * FROM emp ORDER BY sal ,empno DESC

• 查询emp表中记录数：

  SELECT COUNT(comm) FROM emp

• 查询emp表中月薪大于2500的人数：

  SELECT COUNT(*) FROM emp WHERE sal>2500

• 统计月薪与佣金之和大于2500元的人数：

  SELECT COUNT(*) FROM emp WHERE ((sal + IFNULL(comm,0)))>2500

• 查询有佣金的人数，有领导的人数：

  SELECT COUNT(comm),COUNT(mgr) FROM emp

• 查询所有雇员月薪和：

  SELECT SUM(sal) FROM emp

• 查询所有雇员月薪和，以及所有雇员佣金和：

  SELECT SUM(sal),SUM(comm) FROM emp

• 查询所有雇员月薪+佣金和：

  SELECT SUM(sal)+SUM(IFNULL(comm,0)) FROM emp

• 统计所有员工平均工资
  

  SELECT AVG(sal) FROM emp

• 查询最高工资和最低工资：

  SELECT MAX(sal),MIN(sal) FROM emp

• 查询每个部门的部门编号和每个部门的工资和：

  SELECT deptno,SUM(sal) FROM emp GROUP BY deptno

• 查询每个部门的部门编号以及每个部门的人数：

  SELECT deptno,COUNT(*) FROM emp GROUP BY deptno

• 查询每个部门的部门编号以及每个部门工资大于1500的人数

  SELECT deptno ,COUNT(*) FROM emp WHERE sal > 1500 GROUP BY deptno

• 查询工资总和大于9000的部门编号以及工资和：

  SELECT deptno,SUM(sal) FROM emp GROUP BY deptno HAVING SUM(sal)>9000

• 查询5行记录，起始行从0开始

  SELECT *FROM emp LIMIT 0,5

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• 约束

• -主键约束(方法1)

  CREATE TABLE ONE( id INT PRIMARY KEY, NAME VARCHAR(20) )

• 主键约束(方法2)

  CREATE TABLE ONE( id INT , NAME VARCHAR(20), PRIMARY KEY(id) )

• 主键约束(方法3)

  CREATE TABLE ONE( id INT , NAME VARCHAR(20) ); ALTER TABLE ONE ADD CONSTRAINT a PRIMARY KEY(id);

• 自增长约束与唯一约束

  CREATE TABLE ONE( id INT PRIMARY KEY AUTO_INCREMENT, NAME VARCHAR(20) UNIQUE );

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