MySQL错误：每个派生表必须有自己的别名

Question

我收到此错误

  

“每个派生表都必须有自己的别名”

当我运行此查询时

SELECT firstname, lastname, artistId
FROM  artist
WHERE artistId=(
    SELECT artistId
    FROM roles
    WHERE movieCode ='$movie[movieCode]' and  role = 'Director'
) a      

Answer 1

SELECT firstname, lastname, artistId FROM artist WHERE artistId=
  (
    SELECT artistId FROM roles WHERE movieCode ='$movie[movieCode]' AND role = 'Director' AS directorTable
  )

每个表都必须命名。使用第二个SELECT语句创建新表时（因为这就是您正在执行的操作），您需要使用AS子句对其进行命名。

Answer 2

$row1=mysqli_query($conn,"
SELECT firstname, lastname, artistId 
FROM  artist WHERE 
artistId=(SELECT artistId FROM roles WHERE movieCode ='$movie[movieCode]' and  role = 'Director') AS table_alias ")or die(mysqli_error($conn));

这应该有效，每个子查询必须有一个别名“AS”。