mysql alter table修改表命令整理

8、删除employee表中字段Customer_ID的索引,只是将Customer_威斯尼斯人官网 ,ID的索引取消,不会删除Customer_ID字段。

ALTER TABLE employee RENAME Customer

ALTER TABLE employee ADD PRIMARY KEY (ID)

3、修改表employee中的ID字段为主键PRIMARY KEY

6、删除employee表中的Customer_ID字段

MYSQL ALTER
TABLE命令用于修改表结构,例如添加/修改/删除字段、索引、主键等等,本文章通过实例向大家介绍MYSQL
ALTER TABLE语句的使用方法,

ALTER TABLE employee DROP INDEX Customer_ID

MySQL ALTER语法如下:

下面来看几个实例:

ALTER TABLE employee DROP Customer_ID

ALTER TABLE employee CHANGE ID salary INT

5、将employee表中的id字段重命名为salary并设置其数据类型为int

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ALTER TABLE employee ADD UNIQUE (ID)

11、多命令写在一起:

ALTER TABLE employee ADD INDEX (ID)

1、向表employee中添加Account_Number字段并设置其字段类型为INT

ALTER TABLE employee MODIFY First_Name varchar(100)

ALTER [IGNORE] TABLE tbl_name alter_spec [, alter_spec ...] alter_specification: ADD [COLUMN] create_definition [FIRST | AFTER column_name ] or ADD INDEX [index_name] (index_col_name,...) or ADD PRIMARY KEY (index_col_name,...) or ADD UNIQUE [index_name] (index_col_name,...) or ALTER [COLUMN] col_name {SET DEFAULT literal | DROP DEFAULT} or CHANGE [COLUMN] old_col_name create_definition or MODIFY [COLUMN] create_definition or DROP [COLUMN] col_name or DROP PRIMARY KEY or DROP INDEX index_name or RENAME [AS] new_tbl_name or table_options 

7、删除employee表中所有主键

10、将表employee重命名为Customer

2、修改表employee中的ID字段为索引

ALTER TABLE employee ADD COLUMN Account_Number INT

mysql ALTER TABLE Books - ADD PRIMARY KEY (BookID), - ADD CONSTRAINT fk_1 FOREIGN KEY (PubID) REFERENCES Publishers (PubID), - ADD COLUMN Format ENUM('paperback', 'hardcover') NOT NULL AFTER BookName;

4、修改表employee中的ID字段为唯一索引UNIQUE

9、修改employee表中First_Name的字段类型为varchar(100)

ALTER TABLE employee DROP PRIMARY KEY

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