sql所有的alter table语句

以下是 SQL 中所有的 ALTER TABLE 语句：

1. ADD COLUMN：向表中添加新的列

   ALTER TABLE table_name ADD COLUMN column_name data_type;

2. DROP COLUMN：从表中删除列

   ALTER TABLE table_name DROP COLUMN column_name;

3. MODIFY COLUMN：修改列的数据类型或大小

   ALTER TABLE table_name MODIFY COLUMN column_name data_type;

4. RENAME COLUMN：重命名列

   ALTER TABLE table_name RENAME COLUMN old_column_name TO new_column_name;

5. ADD CONSTRAINT：向表中添加约束

   ALTER TABLE table_name ADD CONSTRAINT constraint_name constraint_type (column_name);

6. DROP CONSTRAINT：从表中删除约束

   ALTER TABLE table_name DROP CONSTRAINT constraint_name;

7. RENAME TABLE：重命名表

   ALTER TABLE old_table_name RENAME TO new_table_name;

8. ADD PRIMARY KEY：向表中添加主键

   ALTER TABLE table_name ADD PRIMARY KEY (column_name);

9. DROP PRIMARY KEY：从表中删除主键

   ALTER TABLE table_name DROP PRIMARY KEY;

10. ADD FOREIGN KEY：向表中添加外键

    ALTER TABLE table_name ADD FOREIGN KEY (column_name) REFERENCES other_table_name (other_column_name);

11. DROP FOREIGN KEY：从表中删除外键

    ALTER TABLE table_name DROP FOREIGN KEY foreign_key_name;