DELETE 基础

DELETE 基础要点

• 语法：DELETE FROM 表 WHERE 条件，省略 WHERE 清空整表
• DELETE 逐行删除，写 binlog 与 undo 日志，事务内可回滚
• 自增主键不会因 DELETE 重置，删完再插 id 继续往后
• 带条件删除是日常操作，先 SELECT 看行数更稳
• 连表删除：DELETE 表A FROM 表A JOIN 表B ON 条件
• 大表删除建议分批，DE... LIMIT 循环执行更平稳

DELETE 基础示例

						DELETE FROM user WHERE id = 1001;

						-- 连表删除：删掉没有下过单的用户
						DELETE u FROM user u
						LEFT JOIN orders o ON u.id = o.user_id
						WHERE o.id IS NULL;

DELETE 删除知识点