在MySQL中SQL连接ON不相等 [英] SQL join ON not equal in Mysql

问题描述

我有两个桌子.两者都包含问题ID字段.我想从第二个表中不存在的第一个表中获取所有记录.我不想将"NOT IN"约束用作具有超过40万条记录的第二张表.

I have two tables. Both contains question id field. I want to get all records from first table that are not present in second one. I don't want to use "NOT IN" constrain as second table having more than 400000 records.

推荐答案

尝试类似

SELECt  t1.*
FROM    Table1 t1 LEFT JOIN
        Table2 t2   ON  t1.questionID = t2.questionID
WHERE   t2.questionID IS NULL

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