在 WHERE 子句中转换多个“旧格式”连接

Question

我在 SQL Server 中有以下代码结构。它在 WHERE 子句中使用多个旧格式 *= 连接？

SELECT ....
FROM (select ...) L1,
     (select ...) L2,
     (select ...) SE,
     (select ...) EX,
     (select ...) SE,
     (select ...) Y1,
     (select ...) Y2,
     (select ...) Y3,
     (select ...) Y4,
     (select ...) Y5
WHERE SE.FV = EX.FV
    and SE.FV *= Y1.FV
    and SE.FV *= Y2.FV
    and SE.FV *= Y3.FV
    and SE.FV *= Y4.FV
    and SE.FV *= Y5.FV
    and SE.L1 *= L1.FV
    and SE.L2 *= L2.FV
GROUP BY L1.FV, L1.Descr, L2.FV, L2.Descr
ORDER BY L1.FV, L1.Descr, L2.FV, L2.Descr

在实际代码中，选择是动态生成的 sql 的混搭之母。但本质上，结构如我上面所示。

上述模板的结构应该是什么，以便它使用正确的 LEFT OUTER JOIN 语法，而不改变查询的逻辑？

这样的东西可能有用吗？

SELECT L1.FV, L1.Descr, L2.FV, L2.Descr, Y1.B, Y1.A, Y2.B, Y2.A, ...
FROM (select ...) SE
     LEFT OUTER JOIN (select ...) Y1 ON SE.FV = Y1.FV
        AND LEFT OUTER JOIN (select ...) Y2 ON SE.FV = Y2.FV
        AND LEFT OUTER JOIN (select ...) Y3 ON SE.FV = Y3.FV
        AND LEFT OUTER JOIN (select ...) Y4 ON SE.FV = Y4.FV
        AND LEFT OUTER JOIN (select ...) Y5 ON SE.FV = Y5.FV
        AND LEFT OUTER JOIN (select ...) L1 ON SE.L1 = L1.FV
        AND LEFT OUTER JOIN (select ...) L2 ON SE.L2 = L2.FV,
     (select ...) EX
WHERE SE.FV = EX.FV
GROUP BY L1.FV, L1.Descr, L2.FV, L2.Descr
ORDER BY L1.FV, L1.Descr, L2.FV, L2.Descr

Answer 1

我希望，您的查询可以带入以下结构。

SELECT      L1.FV, 
            L1.Descr, 
            L2.FV, 
            L2.Descr,
            .. 
FROM                (select ...) L1
JOIN/LEFT JOIN      (select ...) L2 ON L2.Col = ....
JOIN/LEFT JOIN      (select ...) SE ON SE.Col = ....
JOIN/LEFT JOIN      (select ...) EX ON EX.Col = ....
JOIN/LEFT JOIN      (select ...) SE ON SE.Col = ....
JOIN/LEFT JOIN      (select ...) Y1 ON Y1.Col = ....
JOIN/LEFT JOIN      (select ...) Y2 ON Y2.Col = ....
JOIN/LEFT JOIN      (select ...) Y3 ON Y3.Col = ....
JOIN/LEFT JOIN      (select ...) Y4 ON Y4.Col = ....
JOIN/LEFT JOIN      (select ...) Y5 ON Y5.Col = ....
GROUP BY L1.FV, L1.Descr, L2.FV, L2.Descr
ORDER BY L1.FV, L1.Descr, L2.FV, L2.Descr;

Answer 2

您可能希望通过使用这样的 CTE 将“动态生成的 sql 的混搭”与 STRUCTURE 分开：

WITH 
    SE AS (select 1 AS X, 2 AS FV, 3 AS L1, 4 AS L2),
    EX AS (select 1 AS X, 2 AS FV),
    Y1 AS (select 1 AS X, 2 AS FV),
    Y2 AS (select 1 AS X, 2 AS FV),
    Y3 AS (select 1 AS X, 2 AS FV),
    Y4 AS (select 1 AS X, 2 AS FV),
    Y5 AS (select 1 AS X, 2 AS FV),
    L1 AS (select 1 AS X, 3 AS FV, 'y' AS Descr),
    L2 AS (select 1 AS X, 4 AS FV, 'z' AS Descr)
SELECT L1.FV, L1.Descr, L2.FV, L2.Descr
FROM 
     SE
     INNER JOIN EX ON EX.FV = SE.FV
     LEFT JOIN Y1 ON Y1.FV = SE.FV
     LEFT JOIN Y2 ON Y2.FV = SE.FV
     LEFT JOIN Y3 ON Y3.FV = SE.FV
     LEFT JOIN Y4 ON Y4.FV = SE.FV
     LEFT JOIN Y5 ON Y5.FV = SE.FV
     LEFT JOIN L1 ON L1.FV = SE.L1
     LEFT JOIN L2 ON L2.FV = SE.L2
GROUP BY L1.FV, L1.Descr, L2.FV, L2.Descr
ORDER BY L1.FV, L1.Descr, L2.FV, L2.Descr