05-表操作2.md

修改数据表

添加单列

ALTER TABLE tb_name ADD [COLUMN] col_name column_definition [FIRST | AFTER col_name]

添加多列

ALTER TABLE tb_name ADD [COLUMN] (col_name column_definition, ...)

删除列

ALTER TABLE tb_name DROP [COLUMN] col_name

多操作同时执行

ALTER TABLE tb_name DROP [COLUMN] col_name, ADD [COLUMN] col_name column_definition

添加主键约束

ALTER TABLE tb_name ADD [CONSTRAINT [symbol]] PRIMARY KEY [index_type] (index_col_name, ...)

添加唯一约束

ALTER TABLE tb_name ADD [CONSTRAINT [symbol]] UNIQUE [INDEX|KEY] [index_name] [index_type] (index_col_name, ...)

添加外键约束

ALTER TABLE tb_name ADD [CONSTRAINT [symbol]] FOREIGN KEY [index_name] (index_col_name, ...) reference_definition

添加/删除默认约束

ALTER TABLE tb_name ALTER [COLUMN] col_name {SET DEFAULT literal | DROP DEFAULT}

删除主键约束

ALTER TABLE tb_name DROP PRIMARY KEY

删除唯一约束

ALTER TABLE tb_name DROP {INDEX|KEY} index_name

删除外键约束

ALTER TABLE tb_name DROP FOREIGN KEY fk_symbol

修改列定义

ALTER TABLE tb_name MODIFY [COLUMN] col_name column_definition [FIRST | AFTER col_name]

修改列名称

ALTER TABLE tb_name CHANGE [COLUMN] old_col_name new_col_name column_definition [FIRST | AFTER col_name]

修改表名

ALTER TABLE tb_name RENAME [TO|AS] new_tb_name

RENAME TABLE tb_name TO new_tab_name [, tb_name2 TO new_tb_name2...]

项目实践中应避免列名及表名的更改，若列名/表名已被调用再更改会影响使用