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有人对如何更好地重构以下有任何建议吗？我已重命名项目名称以简化。

我只继承了这个（用于导入过程），对我来说它看起来不是很有效，尤其是函数中的硬编码值。我正在考虑将硬编码的值放入表中并引用它而不是函数，但我不确定如何根据查询中的重复列来完成这项工作。

MyTable
    MyTableId INT,
    MyTableOtherColumn VARCHAR(100),
    MyTableDesc1 VARCHAR(10),
    MyTableDesc2 VARCHAR(10),
    . . .
    MyTable24 VARCHAR(10),
    MyTable25 VARCHAR(10),
    etc.

MyFunction
    RETURNS @myFunctionTable TABLE
    (
        myFunctionDesc VARCHAR(256),
        myFunctionCode VARCHAR(10)
    )
    AS 
    BEGIN
        INSERT INTO @myFunctionTable (myFunctionDesc, myFunctionCode) VALUES ('My Function Desc 1', 'MYCODE1');
        INSERT INTO @myFunctionTable (myFunctionDesc, myFunctionCode) VALUES ('My Function Desc 2', 'MYCODE2');
        . . .
        INSERT INTO @myFunctionTable (myFunctionDesc, myFunctionCode) VALUES ('My Function Desc 99', 'MYCODE99');
        INSERT INTO @myFunctionTable (myFunctionDesc, myFunctionCode) VALUES ('My Function Desc 100', 'MYCODE100');
    END


SELECT 
    MyTableId,
    MyTableOtherColumn,
    . . . 
    (SELECT myFunctionCode FROM MyFunction() WHERE MyFunctionDesc = MyTableDesc1),
    (SELECT myFunctionCode FROM MyFunction() WHERE MyFunctionDesc = MyTableDesc2),
    . . .
    (SELECT myFunctionCode FROM MyFunction() WHERE MyFunctionDesc = MyTableDesc24),
    (SELECT myFunctionCode FROM MyFunction() WHERE MyFunctionDesc = MyTableDesc25),
FROM myTable T
JOIN . . .
WHERE . . .
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1 回答 1

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只需使用条件聚合和outer apply：

SELECT MyTableId, MyTableOtherColumn,
       . . . 
       mf.val1, mv.val2, . . .
FROM myTable T JOIN
     . . . OUTER APPLY
     (SELECT MAX(CASE WHEN MyFunctionDesc = MyTableDesc1 THEN myFunctionCode END) as val1,
             MAX(CASE WHEN MyFunctionDesc = MyTableDesc2 THEN myFunctionCode END) as val2,
             . . .
      FROM MyFunction()
     ) mf
WHERE . . .
于 2019-08-26T00:29:20.230 回答