sql - 如何在左连接中使用 LEN 函数？

Question

SELECT DISTINCT
        Positions.Issuer_Name
    FROM
     Positions
        LEFT JOIN
        (
            SELECT DISTINCT
              [Assetid]
            FROM
                Report
        ) Report ON
            Report.[Assetid] = Positions.CUSIP //here instead of Report.[Assetid] i need to use `"right([Assetid], Len([Assetid])-1)"`

我需要使用"right([Assetid], Len([Assetid])-1)"它来删除第一个字母并进行比较"Positions.CUSIP"

写这个更好的方法是什么？

而不是像这样写

" ) Report ON Report.right([Assetid], Len([Assetid])-1) = Positions.CUSIP"

我应该先声明变量并先做，"right([Assetid], Len([Assetid])-1)"但是我如何在 JOIN 中使用它呢？

Answer 1

这取决于您要执行的操作，您是要根据当时的right()值进行比较，还是要在以下right()值之前进行比较：

SELECT DISTINCT p.Issuer_Name
FROM Positions p
LEFT JOIN
(
    SELECT DISTINCT Right([Assetid], Len(Assetid)-1) TrimmedAssetid, [Assetid]
    FROM Report
) r 
    ON r.TrimedAssetid = p.CUSIP 

或者

SELECT DISTINCT p.Issuer_Name
FROM Positions p
LEFT JOIN
(
    SELECT DISTINCT [Assetid]
    FROM Report
) r 
    ON Right(r.Assetid,  Len(r.Assetid)-1)) = Positions.CUSIP 

Answer 2

尝试这个 ：

AssetID 是您需要与别名一起使用的列

SELECT DISTINCT
    Positions.Issuer_Name
FROM
 Positions
    LEFT JOIN
    (
        SELECT DISTINCT
          [Assetid]
        FROM
            Report
    ) Report ON
        right(Report.[Assetid], Len(Report.[Assetid])-1) = Positions.CUSIP