判断一个表的数据不在另一个表中最优秀方法
复制代码 代码如下:
table a columns(key,value);
table b columns(key,value);
SELECT a.* FROM a LEFT JOIN b
ON a.key = b.key
WHERE b.key IS NULL
table a columns(key,value);
table b columns(key,value);
SELECT a.* FROM a LEFT JOIN b
ON a.key = b.key
WHERE b.key IS NULL
