mysql的常用查询创建命令

查看所有数据库
Show databases;
创建数据库
Create database 数据库名
删除数据库
Drop database 数据库名
创建表
CREATE TABLE t_bookType(
    id int primary key auto_increment,
    bookTypeName varchar(20),
    bookTypeDesc varchar(200)
);

创建表

CREATE TABLE t_book(
    id int primary key auto_increment,
    bookName varchar(20),
    author varchar(10),
    price decimal(6,2),
    bookTypeId int,
    constraint `fk` foreign key (`bookTypeId`) references `t_bookType`(`id`)
);

desc t_bookType; 查看表结构

show create table t_bookType;查看表结构

alter table t_book rename t_book2; 更改表名

alter table t_book change bookName bookName2 varchar(20);  更改字段

alter table t_book add testField int first ;  增加字段
 
alter table t_book drop testField; 删除字段
 
drop table t_bookType;  删除表

drop table t_book; 删除表

查询学生表

SELECT id,stuName,age,sex,gradeName FROM t_student ;
查询学生表
SELECT stuName,id,age,sex,gradeName FROM t_student ;
查询学生表
SELECT * FROM t_student;
查询学生表
SELECT stuName,gradeName FROM t_student;
查询学生表
SELECT * FROM t_student WHERE id=1;
查询学生表
SELECT * FROM t_student WHERE age>22;
查询学生表
SELECT * FROM t_student WHERE age IN (21,23);

查询学生表
SELECT * FROM t_student WHERE age NOT IN (21,23);
查询学生表
SELECT * FROM t_student WHERE age BETWEEN 21 AND 24;

查询学生表
SELECT * FROM t_student WHERE age NOT BETWEEN 21 AND 24;

SELECT * FROM t_student WHERE stuName LIKE '张三';
SELECT * FROM t_student WHERE stuName LIKE '张三%';
SELECT * FROM t_student WHERE stuName LIKE '张三__';
SELECT * FROM t_student WHERE stuName LIKE '%张三%';

SELECT * FROM t_student WHERE sex IS NULL;
SELECT * FROM t_student WHERE sex IS NOT NULL;

SELECT * FROM t_student WHERE gradeName='一年级' AND age=23
SELECT * FROM t_student WHERE gradeName='一年级' OR age=23

SELECT DISTINCT gradeName FROM t_student;

SELECT * FROM t_student ORDER BY age ASC;
SELECT * FROM t_student ORDER BY age DESC;

SELECT * FROM t_student GROUP BY gradeName;

SELECT gradeName,GROUP_CONCAT(stuName) FROM t_student GROUP BY gradeName;

SELECT gradeName,COUNT(stuName) FROM t_student GROUP BY gradeName;

SELECT gradeName,COUNT(stuName) FROM t_student GROUP BY gradeName HAVING COUNT(stuName)>3;

SELECT gradeName,COUNT(stuName) FROM t_student GROUP BY gradeName WITH ROLLUP;
SELECT gradeName,GROUP_CONCAT(stuName) FROM t_student GROUP BY gradeName WITH ROLLUP;

SELECT * FROM t_student LIMIT 0,5;
SELECT * FROM t_student LIMIT 5,5;
SELECT * FROM t_student LIMIT 10,5;