在SQL中優化查詢

Question

我有以下算法

For R = FirstRowDBABACUS To LastRowDBABACUS ' R = Remboursement
    LastInterestDate = ""
    Do While Sheets("CI").Cells(R, 10).Value <> 0
        For Inte = FirstRowDBABACUS To LastRowDBABACUS
            'On commence par l'intérêt
            If Sheets("CI").Cells(Inte, 3).Value <= DateArrete Then
                LastInterestDate = "R" & Inte & "C" & 3
                If Sheets("CI").Cells(Inte, 8).Value <> 0 Then
                    If Sheets("CI").Cells(R, 10).Value > Sheets("CI").Cells(Inte, 8).Value Then
                        'Modification du montant de Remboursement residuel
                        Sheets("CI").Cells(R, 10).Value = Sheets("CI").Cells(R, 10).Value - Sheets("CI").Cells(Inte, 8)
                        Sheets(RapproSheetName).Cells(Inte, 12).Value = Sheets(RapproSheetName).Cells(Inte, 8).Value
                        Sheets("CI").Cells(Inte, 8).Value = 0
                    Else
                        'Le montant ne suffit pas pour les intérêts
                        Sheets(RapproSheetName).Cells(Inte, 12).Value = Sheets(RapproSheetName).Cells(Inte, 12).Value + Sheets("CI").Cells(R, 10).Value
                        Sheets("CI").Cells(Inte, 8).Value = Sheets("CI").Cells(Inte, 8).Value - Sheets("CI").Cells(R, 10).Value
                        Sheets("CI").Cells(R, 10).Value = 0
                        Exit For
                    End If
                End If
                'Principal s'il reste quelque chose
                If Sheets("CI").Cells(R, 10).Value <> 0 Then
                    If Sheets("CI").Cells(Inte, 9) <> 0 Then
                        If Sheets("CI").Cells(R, 10).Value > Sheets("CI").Cells(Inte, 9).Value Then
                            'Modification du montant de Remboursement residuel
                            Sheets("CI").Cells(R, 10).Value = Sheets("CI").Cells(R, 10).Value - Sheets("CI").Cells(Inte, 9)
                            Sheets(RapproSheetName).Cells(Inte, 11).Value = Sheets(RapproSheetName).Cells(Inte, 9).Value
                            Sheets("CI").Cells(Inte, 9).Value = 0
                        Else
                            'Le montant ne suffit pas pour le remboursmeent du principal
                            Sheets(RapproSheetName).Cells(Inte, 11).Value = Sheets(RapproSheetName).Cells(Inte, 11).Value + Sheets("CI").Cells(R, 10).Value
                            Sheets("CI").Cells(Inte, 9).Value = Sheets("CI").Cells(Inte, 9).Value - Sheets("CI").Cells(R, 10).Value
                            Sheets("CI").Cells(R, 10).Value = 0
                            Exit For
                        End If
                    End If
                End If
            Else

            End If
        Next Inte

我正在嘗試編寫代碼sql，它花費的時間太長且結果錯誤。

>   declare @RefAbacus as nvarchar(100)
>     set @RefAbacus ='002-00000001'
>     SELECT
>       RowNum = ROW_NUMBER() OVER (
>       ORDER BY [RefAbacus]),
>       * INTO #CI
>     FROM [CI]
>     WHERE [RefAbacus] = @RefAbacus
>     order by date, TypeOperation
>     SELECT
>       RowNum = ROW_NUMBER() OVER (
>       ORDER BY [RefAbacus]),
>       * INTO #DBRapproEchRemb
>     FROM [DBTmpRapproEchRemb]
>     WHERE [RefAbacus] =@RefAbacus
>     order by date, TypeOperation
>     
>     CREATE UNIQUE CLUSTERED INDEX IX_1 on #CI ([RefAbacus], RowNum)
>     CREATE UNIQUE CLUSTERED INDEX IX_2 on #DBRapproEchRemb ([RefAbacus], RowNum)
>     --declaration des variables
>     DECLARE @MaxRownum int
>     SET @MaxRownum = (SELECT
>       MAX(RowNum)
>     FROM #CI) -----------------------
>     DECLARE @MinRownum int
>     SET @MinRownum = (SELECT
>       MIN(RowNum)
>     FROM #CI)
>     
>     DECLARE @FR int;
>     DECLARE @LR int;
>     DECLARE @inte int;
>     DECLARE @R int;
>     DECLARE @remboursement AS float
>     DECLARE @LastInterestDate AS nvarchar(50);
>     DECLARE @i int;
>     DECLARE @TolerancePart int;
>     
>     SET @FR = @MinRownum
>     SET @LR = @MaxRownum
>     SET @TolerancePart = 5;
>     ----------------------------------------------------
>     
>     SET @R = (SELECT
>       MIN(RowNum)
>     FROM #CI)
>     SET @inte = (SELECT
>       MIN(RowNum)
>     FROM #CI)
>     
>     
>           WHILE @R <= @MaxRownum
>               BEGIN
>               
>                   while  (SELECT [Remboursement] FROM #CI WHERE RowNum = @R ) <>0  and   (SELECT [Remboursement] FROM #CI WHERE RowNum = @R ) IS NOT
> NULL
>                   begin
>                   SET @LastInterestDate = ''
>                   SET @inte = (SELECT
>                     MIN(RowNum)
>                   FROM #CI)-1
>                       WHILE @inte <= @MaxRownum
>                           BEGIN -- run your operation here
>                       --print @inte
>                           -- Condition 1
>                               SET @inte = @inte + 1;
>                           IF (SELECT Date FROM #CI WHERE RowNum = @inte)<= CONVERT(date, GETDATE())
>     
>                               BEGIN
>                               SET @LastInterestDate = 'R' + CONVERT(nvarchar(50), @inte) + 'C3'
>     
>                               -- Condition 2
>                               IF ((SELECT EchInteret FROM #CI
>                               WHERE RowNum = @inte) <> 0)
>                                   BEGIN
>                           
>                                   -- Condition 3 
>                                   IF ((SELECT [Remboursement] FROM #CI 
>                                   WHERE RowNum = @R) > (SELECT EchInteret FROM #CI
>                                   WHERE RowNum = @inte))
>                                       BEGIN ---------------------------------------
>                                       -- Update 1
>                                       print 'Update 1'
>                                       UPDATE #CI
>                                       SET [Remboursement] = R.[Remboursement] - isnull(INTE.EchInteret,0)
>                                       FROM (SELECT * FROM #CI
>                                       WHERE RowNum = @inte) INTE INNER JOIN (SELECT  * FROM #CI
>                                       WHERE RowNum = @R) R
>                                       ON R.RefAbacus = INTE.RefAbacus WHERE #CI.RowNum = @R; 
>                               
>                                       -- Update 2
>                                       UPDATE #CI
>                                       SET EchInteret = 0
>                                       FROM (SELECT * FROM #CI
>                                       WHERE RowNum = @inte) INTE INNER JOIN (SELECT  * FROM #CI
>                                       WHERE RowNum = @R) R ON R.RefAbacus = INTE.RefAbacus
>                                       WHERE #CI.RowNum = @inte; 
>                                   
>                                       UPDATE #DBRapproEchRemb
>                                       SET [PartEnInterêt] = isnull(EchInteret,0)
>                                       WHERE RowNum = @inte;
>     
>     
>                                       --SET @inte = @inte + 1;
>                                       END
>                                       ELSE -------------------------
>                                       -- Update 3
>                                       BEGIN
>     
>                                       UPDATE #DBRapproEchRemb
>                                       SET [PartEnInterêt] = isnull(INTE.[PartEnInterêt],0) + R.Remboursement
>                                       FROM (SELECT * FROM #CI
>                                       WHERE RowNum = @R) R
>                                       INNER JOIN (SELECT * FROM #DBRapproEchRemb
>                                       WHERE RowNum = @inte) INTE ON R.RefAbacus = INTE.RefAbacus
>                                       WHERE #DBRapproEchRemb.RowNum = @inte;
>     
>     
>                                       UPDATE #CI
>                                       SET EchInteret = isnull(INTE.EchInteret,0) - R.Remboursement
>                                       FROM (SELECT * FROM #CI
>                                       WHERE RowNum = @R) R INNER JOIN (SELECT * FROM #CI
>                                       WHERE RowNum = @inte) INTE ON R.RefAbacus = INTE.RefAbacus
>                                       WHERE #CI.RowNum = @inte;
>     
>                                       print 'ok'
>                                       UPDATE #CI
>                                       SET Remboursement = 0
>                                       WHERE #CI.RowNum = @R;
>     
>                                       --------------------------------------------
>                                       BREAK
>                                       END
>                                   END
>     
>                                   -- Condition 4 
>                                   IF ((SELECT [Remboursement]FROM #CI
>                                   WHERE RowNum = @R) <> 0)
>     
>                                   BEGIN
>                                   -- Condition 5
>                                   IF ((SELECT EchPrincial FROM #CI
>                                   WHERE RowNum = @inte) <> 0)
>     
>                                       BEGIN
>                                   
>                                       -- Condition 6
>                                       IF ((SELECT [Remboursement] FROM #CI
>                                       WHERE RowNum = @R) > (SELECT EchPrincial FROM #CI
>                                       WHERE RowNum = @inte))
>     
>                                           -- Update 4
>     
>                                           BEGIN
>                                           ----------------------------
>                                           
>                                           UPDATE #CI
>                                           SET [Remboursement] = R.[Remboursement] - isnull(INTE.EchPrincial,0)
>                                           FROM (SELECT*FROM #CI
>                                           WHERE RowNum = @inte) INTE INNER JOIN (SELECT * FROM #CI
>                                           WHERE RowNum = @R) R ON R.RefAbacus = INTE.RefAbacus
>                                           WHERE #CI.RowNum = @R;
>                                       
>                                           UPDATE #DBRapproEchRemb
>                                           SET PartEnPrincipal =isnull( EchPrincial,0)
>                                           WHERE RowNum = @inte;
>     
>     
>                                           UPDATE #CI
>                                           SET EchPrincial = 0
>                                           WHERE #CI.RowNum = @inte;
>                                           print' avant break'
>     
>                                           END
>                                           -----------
>                                       ELSE
>                                           -- Update 5
>                                           BEGIN
>                                       
>     
>                                           UPDATE INTE
>                                           SET PartEnPrincipal = isnull(inte.PartEnPrincipal,0) + R.Remboursement
>                                           FROM (SELECT * from #DBRapproEchRemb 
>                                            WHERE RowNum = @inte)INTE INNER JOIN (SELECT * FROM #CI
>                                           WHERE RowNum = @R) R ON R.RefAbacus = INTE.RefAbacus
>                                           WHERE INTE.RowNum = @inte;
>     
>     
>                                           UPDATE INTE
>                                           SET EchPrincial = inte.EchPrincial + R.Remboursement
>                                           FROM #CI
>                                           INTE INNER JOIN (SELECT * FROM #CI
>                                           WHERE RowNum = @R) R ON R.RefAbacus = INTE.RefAbacus
>                                           WHERE INTE.RowNum = @inte;
>     
>     
>                                           UPDATE #CI
>                                           SET Remboursement = 0
>                                           WHERE #CI.RowNum = @R;
>                                           print 'apres break'
>                                           
>                                           BREAK
>                                           END
>                                       END
>     
>                               END
>     
>                           END
>                   
>                           end
>     
>               END
>                   SET @R = @R + 1;
>           END

。 。 。

Answer 1

您要做的第一件事就是獲取SQL以獲得正確的結果。 優化沒有產生正確結果的東西是沒有意義的。 這里的不幸消息是，在您完成特定的優化之前，我們無法真正為您提供幫助，因為我們需要知道正確的查詢是什么樣子。

完成此操作后，下一步就是調查執行計划，並查看查詢的內容。 您將要弄清楚查詢的哪一部分是最昂貴的部分，然后首先開始對該部分進行優化。 好的工具不僅會向您顯示計划的每個部分，而且還會顯示這些部分相對於計划的其余部分所花費的時間。 如果查詢或查詢批處理中有多個不同的語句，則還應顯示哪些語句最昂貴。 如果您使用的是SQL Server，則SQL Server Management Studio工具附帶了可接受的查詢計划查看器，該查看器提供了此類信息，如果丟失索引，甚至可以幫助建議索引。 例如，如果您要進行表掃描（獲取全部或很大一部分），則表將數百萬行僅用於查找一些值，這將導致性能不理想。 或者，如果您要對非常大的數據集進行排序，那么也會導致性能下降。 您的查詢也顯式循環。 如果它在大量行上循環，那將是昂貴的。 如果您可以嘗試擺脫顯式循環而轉而使用基於集合的操作，則查詢優化器可能能夠簡化某些步驟並極大地加快操作速度。 但這只是猜測，因為目前我沒有足夠的信息來幫助您。

但是，除此之外，除非我們知道有效的查詢（產生正確結果的查詢），您正在使用的特定SQL數據庫，架構的外觀以及各種表的大小，否則它將不會我們很容易為您提供具體建議。