mysql - Delete from table when field does not match another table in MySQL

Question

I'm trying to use the following SELECT statement to craft a DELETE statement after I get it working.

Basically table "listing" has a bunch of record that need to be removed. If the EmpNo cannot be found in address table then I want to remove the record from listing table. I keep getting a invalid syntax. What am I doing wrong?

SELECT A.*
FROM address A
LEFT JOIN listing B
USING (EmpNo)
WHERE B.EmpNo IS <> A.EmpNo

Answer 1

在此处删除IS关键字：

WHERE B.EmpNo IS <> A.EmpNo

应该：

WHERE B.EmpNo  <> A.EmpNo

如果EmpNo在两个表中都存在同名，USING则将在那里正常工作。否则，您可以更明确一点ON：

FROM 
  address A
  LEFT JOIN listing B
    ON A.EmpNo = B.EmpNo

要在 中查找A不匹配的记录B，请测试B.EmpNo IS NULL而不是B.EmpNo <> A.EmpNo。

WHERE B.EmpNo IS NULL