mysql查询左边连接多个值

Question

这是我的sql数据fiddler http://sqlfiddle.com/#!2/63178/1。我的查询出了什么问题？

SELECT DISTINCT curr.id,curr.curr_tittle, curr.curr_desc 
FROM  wp_curriculum curr LEFT JOIN (SELECT DISTINCT * FROM wp_curriculum_topic WHERE curr_topic IN (4,12)) AS A ON A.curr_id = curr.id ORDER BY A.id

Answer 1

如果您要查找表中的匹配行，则只需将LEFT JOIN替换为INNER JOIN，否则您的sql查询将显示LEFT JOIN条件的预期结果。

使用INNER JOIN的SQL查询：

SELECT DISTINCT curr.id,curr.curr_tittle, curr.curr_desc FROM  wp_curriculum curr INNER JOIN (SELECT DISTINCT * FROM wp_curriculum_topic WHERE curr_topic IN (4,12)) AS A ON curr.id = A.curr_id ORDER BY A.id

Answer 2

您的查询按预期工作。可能是你正在混合ID和CURR_ID？