用别名不就行了嘛 SELECT a.A FROM table a LEFT JOIN table b ON a.A=b.B WHERE b.B IS NULL;
SELECT a.knowledgekind FROM knowledge a LEFT JOIN knowledge b ON a.knowledgekind=b.knowledgename WHERE b.knowledgename IS NULL;Error Code : 1046 No Database Selected (10 ms taken)出错,还麻烦心帆帮忙看一下,多谢!
SELECT a.A FROM table a LEFT JOIN table b ON a.A=b.B WHERE b.B IS NULL;
No Database Selected
(10 ms taken)出错,还麻烦心帆帮忙看一下,多谢!
No Database Selected .....!!!!