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  • MySQL第三课

    首先创建一个数据库:

    CREATE DATABASE ku;

    Query OK, 1 row affected

    查看一下是否有此数据库:

    SHOW DATABASES;

    +--------------------+
    | Database           |
    +--------------------+
    | information_schema |
    | ku                 |
    | mysql              |
    | performance_schema |
    | test               |
    +--------------------+
    5 rows in set

    使用此数据库:

     USE ku;
    Database changed

    创建数据表:

     CREATE TABLE biao(
        name VARCHAR(20),
        age INT(11),
        sex CHAR(11),
        love VARCHAR(11)
        );
    Query OK, 0 rows affected

    查看表结构:

    DESC biao;
    +-------+-------------+------+-----+---------+-------+
    | Field | Type        | Null | Key | Default | Extra |
    +-------+-------------+------+-----+---------+-------+
    | name  | varchar(20) | YES  |     | NULL    |       |
    | age   | int(11)     | YES  |     | NULL    |       |
    | sex   | char(11)    | YES  |     | NULL    |       |
    | love  | varchar(11) | YES  |     | NULL    |       |
    +-------+-------------+------+-----+---------+-------+
    4 rows in set

    修改表名:

    ALTER TABLE biao RENAME biao1;

    Query OK, 0 rows affected

    修改字段和类型:

    ALTER TABLE biao1 CHANGE SEX SEX1 CHAR(20);
    Query OK, 0 rows affected
    Records: 0  Duplicates: 0  Warnings: 0

    用圆括号!!!!

    再查看一边:

    DESC biao1;
    +-------+-------------+------+-----+---------+-------+
    | Field | Type        | Null | Key | Default | Extra |
    +-------+-------------+------+-----+---------+-------+
    | name  | varchar(20) | YES  |     | NULL    |       |
    | age   | int(11)     | YES  |     | NULL    |       |
    | SEX1  | char(20)    | YES  |     | NULL    |       |
    | love  | varchar(11) | YES  |     | NULL    |       |
    +-------+-------------+------+-----+---------+-------+
    4 rows in set

    修改字段的排列位置:

    ALTER TABLE biao1 MODIFY NAME VARCHAR(20) AFTER SEX1;
    Query OK, 0 rows affected
    Records: 0  Duplicates: 0  Warnings: 0

    查看:

    DESC biao1;
    +-------+-------------+------+-----+---------+-------+
    | Field | Type        | Null | Key | Default | Extra |
    +-------+-------------+------+-----+---------+-------+
    | age   | int(11)     | YES  |     | NULL    |       |
    | SEX1  | char(20)    | YES  |     | NULL    |       |
    | NAME  | varchar(20) | YES  |     | NULL    |       |
    | love  | varchar(11) | YES  |     | NULL    |       |
    +-------+-------------+------+-----+---------+-------+
    4 rows in set

    注意改的是大写出现的也是大写

    加一个think字段:

    ALTER TABLE biao1 ADD think VARCHAR (10) AFTER LOVE;
    Query OK, 0 rows affected
    Records: 0  Duplicates: 0  Warnings: 0

    查看:

    DESC biao1;
    +-------+-------------+------+-----+---------+-------+
    | Field | Type        | Null | Key | Default | Extra |
    +-------+-------------+------+-----+---------+-------+
    | age   | int(11)     | YES  |     | NULL    |       |
    | SEX1  | char(20)    | YES  |     | NULL    |       |
    | NAME  | varchar(20) | YES  |     | NULL    |       |
    | love  | varchar(11) | YES  |     | NULL    |       |
    | think | varchar(10) | YES  |     | NULL    |       |
    +-------+-------------+------+-----+---------+-------+
    5 rows in set

    删除think:

    ALTER TABLE biao1 DROP think;
    Query OK, 0 rows affected

    Records: 0  Duplicates: 0  Warnings: 0

    查看:

    DESC biao1;
    +-------+-------------+------+-----+---------+-------+
    | Field | Type        | Null | Key | Default | Extra |
    +-------+-------------+------+-----+---------+-------+
    | age   | int(11)     | YES  |     | NULL    |       |
    | SEX1  | char(20)    | YES  |     | NULL    |       |
    | NAME  | varchar(20) | YES  |     | NULL    |       |
    | love  | varchar(11) | YES  |     | NULL    |       |
    +-------+-------------+------+-----+---------+-------+
    4 rows in set

    删除此表:

    DROP TABLE biao1;
    Query OK, 0 rows affected

    查看:

    SHOW TABLES;
    Empty set

    删除数据库:

    DROP DATABASE ku;
    Query OK, 0 rows affected

    查看:

    SHOW DATABASES;
    +--------------------+
    | Database           |
    +--------------------+
    | information_schema |
    | mysql              |
    | performance_schema |
    | test               |
    +--------------------+
    4 rows in set

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  • 原文地址:https://www.cnblogs.com/zmh0227/p/11816250.html
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