我想知道SQL Server 2005中是否可以使用以下内容。在我的实际存储过程中使用其他case语句计算A列和B列。我不想在不必要的情况下对另一个字段重复相同的操作。如果这在语法上不可能,还有其他想法吗?
SELECT A, B, CASE WHEN column1='1' THEN A ELSE B END Col1.
按要求提供的实际查询的修改版本。 CTE在这个模型中看起来很难。 WANNABE是我想在子选择语句中完成的列。
SELECT 1 AS Region, 'Test',
CAST(Work AS NUMERIC(18,2)) Work,
Work + 2 AS Work2,
WANNABE
FROM
(
SELECT
ROW_NUMBER() OVER(PARTITION BY G.Value, C.C, FR.Mod1 ORDER BY FR.Date DESC, FG.Date DESC, FC.Date DESC) ROW,
CASE WHEN COALESCE(FR.Mod1, '') = '' THEN '' ELSE FR.Mod1 END Mod1,
CASE WHEN @var1=1 AND @var2 = 1 THEN FR.Col1 * G.Value
WHEN @var1=1 AND @var2 = 0 THEN FP.Col1 * G.Value END Work,
CASE WHEN 1=1 THEN Work ELSE 1 END WANNABE,
(
SELECT Col3
FROM Table2
WHERE c = FR.Value
) AS Custom
FROM MainTable FR
JOIN @C C ON FR.Col2 = C.Col2
LEFT JOIN Function1(@VersionDate) cv ON cv.Code = C.Code
LEFT JOIN Function2(@VersionDate) hv ON hv.Code = C.Code
LEFT JOIN @G G ON 1 = 1
LEFT JOIN SubTable1 FG ON FG.Number = G.Value, 2 AND FG.Date = @VersionDate
LEFT JOIN SubTable2 FO ON FO.Number = G.Value
AND FO.Date = @VersionDate AND FO.Code = FR.Code AND FR.Mod1 = FO.Mod1
LEFT JOIN SubTable3 FP ON FP.Code = FR.Code AND FP.VersionDate = @Versiondate
AND CASE WHEN DATALENGTH(FR.Mod1) = 0 THEN '00' ELSE FR.Mod1 END = CASE WHEN DATALENGTH(FP.Mod1) = 0 THEN '00' ELSE FP.Mod1 END
LEFT JOIN SubTable4 FC ON FC.Date = @VersionDate
WHERE FR.Date = @VersionDate
) x
WHERE x.Row = 1
AND RTRIM(LTRIM(x.Col1)) IN ('', '2')
答案 0 :(得分:3)
您可以在CTE中定义A,B
列别名,然后在外部选择中引用它们。
;WITH CTE AS
(
SELECT CASE ... END AS A,
CASE ... END AS B,
column1
FROM your_table
)
SELECT A,
B,
CASE WHEN column1='1' THEN A ELSE B END Col1
FROM CTE
类似地,您也可以在CROSS APPLY
中定义它们,有时候会稍微冗长一些。
显示语法的一个愚蠢的例子是
SELECT A,
B,
CASE WHEN type='P' THEN A ELSE B END Col1
FROM master..spt_values
CROSS APPLY (SELECT CASE WHEN number %2 = 1 THEN 1 END,
CASE WHEN number %2 = 0 THEN 0 END) T(A,B)
更新后,您可以使用CTE替换派生表并按如下方式嵌套CTE
;WITH x as
(
SELECT
ROW_NUMBER() OVER(PARTITION BY G.Value, C.Code, FR.Mod1 ORDER BY FR.Date DESC, FG.Date DESC, FC.Date DESC) ROW,
...<snip>
WHERE FR.Date = @VersionDate
),
x2 As
(
SELECT *,
CASE WHEN 1=1 THEN Work ELSE 1 END WANNABE
FROM x
)
SELECT 1 AS Region, 'Test',
CAST(Work AS NUMERIC(18,2)) Work,
Work + 2 AS Work2,
WANNABE
FROM x2
WHERE x2.Row = 1
AND RTRIM(LTRIM(x2.Col1)) IN ('', '2')
答案 1 :(得分:0)
是的,这是可能的,但你的所有sql语句怎么样?您可以在使用时在select语句中使用case语句。 像这样的东西
SELECT SUM((CASE WHEN column1='1' THEN 10 ELSE 0 END)) AS A, SUM((CASE WHEN column1='2' THEN 10 ELSE 0 END)) AS B
FROM YourTable