Question

我的SQL Server中有两个表

表号1

CREATE TABLE #Config
(
  varColumnName VARCHAR(200) ,
  varAliasName VARCHAR(200)
)

INSERT INTO #Config (varColumnName, varAliasName)
VALUES ('Consumed (Strips)', 'decQuantity'),
       ('Closing (Strips)', 'decClosing')

表号2

CREATE TABLE #Data
(
    decQuantity DECIMAL(18, 2) ,
    decClosing DECIMAL(18, 2) ,
    varInvalidRemarks VARCHAR(MAX)
)

INSERT INTO #Data (decQuantity, decClosing)
VALUES (10.10, 25.00),
       (-15.10, 45.00),
       (5.10, -10.00),
       (-25.10, -10.00)

从这两个表中我想更新#Data表的varInvalidRemarks列，我想要以下输出：

 decQuantity  | decClosing |  varInvalidRemarks
 -------------|------------|--------------------------
       10.10  |     25.00  |    
      -15.10  |     45.00  |  Consumed (Strips) can NOT be negetive
        5.10  |    -10.00  |  Closing (Strips) can NOT be negetive
      -25.10  |    -10.00  |  Consumed (Strips) can not be negetive,Closing(Strips) can not be negetive

我用FAST FORWARD READ ONLY光标做了这件事，但我想用子查询或动态查询来做。

DECLARE @varColumnName VARCHAR(200) ,
@varAliasName VARCHAR(200)

DECLARE DisplayColumn CURSOR FAST_FORWARD READ_ONLY
FOR
SELECT  C.varColumnName ,
        C.varAliasName
FROM    #Config AS C

OPEN DisplayColumn

FETCH NEXT FROM DisplayColumn INTO @varColumnName, @varAliasName

WHILE @@FETCH_STATUS = 0
BEGIN
    EXEC ('
    UPDATE  D
    SET     D.varInvalidRemarks = isnull(D.varInvalidRemarks,'''') +
    '','+@varColumnName +' can not be negative ''
    FROM    #Data AS D
    WHERE   CAST(ISNULL(D.'+@varAliasName+', 0) AS DECIMAL(18, 2)) < 0

    ')

    FETCH NEXT FROM DisplayColumn INTO @varColumnName, @varAliasName

END

CLOSE DisplayColumn
DEALLOCATE DisplayColumn

我想这样做是因为我的存储过程中的性能问题。

是否可以通过子查询实现这一点？

由于

Answer 1

这是一个动态SQL解决方案。请参阅PRINT以获取动态查询

declare @sql    nvarchar(max),
    @col    nvarchar(max)

select  @col    = isnull(@col + 'UNION ALL' + char(13), '')
        + 'SELECT rmk = ''' + c.varColumnName + ' cannot be negative'' WHERE ' + quotename(c.varAliasName) + ' < 0' + char(13)
from    #Config c

select  @sql    = isnull(@sql, '')
        + N'UPDATE D SET varInvalidRemarks = STUFF(V.Remarks, 1, 1, '''')'  + char(13)
        + N'FROM #Data D'                           + char(13)
        + N'OUTER APPLY'                            + char(13)
        + N'('                                  + char(13)
        + N'SELECT '','' + rmk'                         + char(13)
        + N'FROM'                               + char(13)
        + N'('                                  + char(13)
        + @col                                  + char(13)
        + N') V'                                + char(13)
        + N'FOR XML PATH ('''')'                        + char(13)
        + N') V (Remarks)'                          + char(13)
FROM    #Config c

print   @col
print   @sql
exec    sp_executesql @sql

Answer 2

您可以制作此类存储过程，而不是使用游标。

UPDATE #Data
SET varInvalidRemarks = ISNULL(
           STUFF((SELECT CASE WHEN decQuantity < 0 THEN ',Consumed (Strips) cannot be negative' ELSE '' END
                          + CASE WHEN decClosing < 0 THEN ',Closing (Strips) cannot be negative' ELSE '' END
               ),1,1,''),
           ''
       )

Answer 3

这样的事情应该有效：

UPDATE #Data
SET varInvalidRemarks = 
  CASE
  WHEN decQuantity < 0 AND decClosing < 0
    THEN 'Consumed (Strips) can NOT be negative,Closing(Strips) can not be negative'
  WHEN decQuantity < 0
    THEN 'Consumed (Strips) can NOT be negetive'
  WHEN decClosing < 0
    THEN 'Closing (Strips) can NOT be negetive'
  ELSE NULL
  END

Answer 4

我之前评论过，您可以使用CASE表达式执行UPDATE：

UPDATE #Data
    SET varInvalidremarks = STUFF((
        SELECT
            CASE WHEN decQuantity < 0 THEN ',Consumed (Strips) cannot be negative' ELSE '' END +
            CASE WHEN decClosing < 0 THEN ',Closing (Strips) cannot be negative' ELSE '' END 
        ),1, 1, '')

但是，如果可以随时修改#config.varColumnName，则硬编码的CASE表达式将无效。相反，您可以使用CROSS APPLY动态获取varColumnName：

UPDATE d
    SET varInvalidremarks = STUFF((
        SELECT
            CASE WHEN d.decQuantity < 0 THEN ',' + c.decQuantity + ' cannot be negative' ELSE '' END +
            CASE WHEN d.decClosing < 0 THEN ',' + c.decClosing +' cannot be negative' ELSE '' END 
        ),1, 1, '')
FROM #Data d
CROSS APPLY(
    SELECT
        decQuantity = MAX(CASE WHEN varAliasName = 'decQuantity' THEN varColumnName END),
        decClosing  = MAX(CASE WHEN varAliasName = 'decClosing' THEN varColumnName END)
    FROM #Config
) c

使用SQL子查询或动态查询

4 个答案: