mysql– 如果sql中不存在,则插入记录,重复列名

概述我想要一个解决方案来插入一个记录,如果它不存在所以我在这里搜索并找到了解决方案,但我有另一个问题INSERT INTO closed_answers (question_id, subject_id) SELECT * FROM (SELECT 2, 2) AS tmp WHERE NOT EXISTS ( SELECT question_id FR

我想要一个解决方案来插入一个记录,如果它不存在所以我在这里搜索并找到了解决方案,但我有另一个问题

INSERT INTO closed_answers (question_ID,subject_ID)SELECT * FROM (SELECT 2,2) AS tmpWHERE NOT EXISTS (    SELECT question_ID FROM closed_answers WHERE question_ID = 2 AND subject_ID = 2) liMIT 1

输出是

#1060 - Duplicate column name '2'

如果我使用任何不相同的2个数字它将起作用,但当2个数字相同时出现问题最佳答案使sql工作的最小变化是为select语句添加别名：

INSERT INTO closed_answers (question_ID,subject_ID)SELECT * FROM (SELECT 2 AS question_ID,2 AS subject_ID) AS tmpWHERE NOT EXISTS (    SELECT question_ID    FROM closed_answers    WHERE question_ID = 2 AND subject_ID = 2) liMIT 1

但是,如果您对(question_ID,subject_ID)有唯一约束,则可以使用INSERT IGnorE：

INSERT IGnorE INTO closed_answers (question_ID,subject_ID)VALUES (2,2)

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