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  • 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;

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  • 原文地址:https://www.cnblogs.com/gyadmin/p/8426315.html
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