mysql_数据表的修改操作

• 删除列：ALTER TABLE tb1_name DROP[COLUMN] col_name;

• 添加多列：ALTER TABLE tb1_name ADD[COLUMN] (col_name column_definition,...);

• 添加单列：ALTER TABLE tb!_name ADD[COLUMN] col_name column_definition [FIRST|AFTER col_name];

• 条件删除：DELETE FROM province WHERE id=3;

• 添加主键约束 ALTER TABLE table_name ADD [CONSTRAINT [symbol]] PRIMARY KEY [index_type] (index_col_name,...)

• 添加唯一约束 ALTER TABLE table_name ADD [CONSTRAINT [symbol]] UNIQUE [INDEX | KEY] [index_name] [index_type] (index_col_name, ...)

• 添加外键约束 ALTER TABLE table_name ADD [CONSTRAINT [symbol]] FOREIGN KEY [index_name] (index_col_name, ...) REFERENCES_definition;

添加外键约束：ALTER TABLE users2 ADD FOREIGN KEY(pid) REFERENCES provinces (id);

添加默认约束：ALTER TABLE users2 ALTER age SET DEFAULT 15;

删除默认约束：ALTER TABLE users2 ALTER age DROP DEFAULT;

修改定义列

ALTER TABLE tb1_name MODIFY [COLUMN] col_name column_definition [FIRST|AFTER col_name]

ALTER TABLE table_name id SAMLLINT UNSIGNED NOT NULL FIRST; // 把id放到第一列

修改列名称

ALTER TABLE table_name CHANGE [COLUMN] old_col_name new_col_name column_deinition [FIRST|AFTER col_name]

ALTER TABLE users CHANGE pid p_id TINYINT UNSIGNED NOT NULL

约束|修改表