J'essaie de régler une requête dans laquelle la même fonction table (TVF) est appelée sur 20 colonnes.
La première chose que j'ai faite a été de convertir la fonction scalaire en une fonction de valeur de table en ligne.
La méthode CROSS APPLYla plus performante consiste-t-elle à exécuter la même fonction sur plusieurs colonnes dans une requête?
Un exemple simpliste:
SELECT Col1 = A.val
,Col2 = B.val
,Col3 = C.val
--do the same for other 17 columns
,Col21
,Col22
,Col23
FROM t
CROSS APPLY
dbo.function1(Col1) A
CROSS APPLY
dbo.function1(Col2) B
CROSS APPLY
dbo.function1(Col3) C
--do the same for other 17 columnsExiste-t-il de meilleures alternatives?
La même fonction peut être appelée dans plusieurs requêtes sur un nombre X de colonnes.
Voici la fonction:
CREATE FUNCTION dbo.ConvertAmountVerified_TVF
(
@amt VARCHAR(60)
)
RETURNS TABLE
WITH SCHEMABINDING
AS
RETURN
(
WITH cteLastChar
AS(
SELECT LastChar = RIGHT(RTRIM(@amt), 1)
)
SELECT
AmountVerified = CAST(RET.Y AS NUMERIC(18,2))
FROM (SELECT 1 t) t
OUTER APPLY (
SELECT N =
CAST(
CASE
WHEN CHARINDEX(L.LastChar COLLATE Latin1_General_CS_AS, '{ABCDEFGHI}', 0) >0
THEN CHARINDEX(L.LastChar COLLATE Latin1_General_CS_AS, '{ABCDEFGHI}', 0)-1
WHEN CHARINDEX(L.LastChar COLLATE Latin1_General_CS_AS, 'JKLMNOPQR', 0) >0
THEN CHARINDEX(L.LastChar COLLATE Latin1_General_CS_AS, 'JKLMNOPQR', 0)-1
WHEN CHARINDEX(L.LastChar COLLATE Latin1_General_CS_AS, 'pqrstuvwxy', 0) >0
THEN CHARINDEX(L.LastChar COLLATE Latin1_General_CS_AS, 'pqrstuvwxy', 0)-1
ELSE
NULL
END
AS VARCHAR(1))
FROM
cteLastChar L
) NUM
OUTER APPLY (
SELECT N =
CASE
WHEN CHARINDEX(L.LastChar COLLATE Latin1_General_CS_AS, '{ABCDEFGHI}', 0) >0
THEN 0
WHEN CHARINDEX(L.LastChar COLLATE Latin1_General_CS_AS, 'JKLMNOPQRpqrstuvwxy', 0) >0
THEN 1
ELSE 0
END
FROM cteLastChar L
) NEG
OUTER APPLY(
SELECT Amt= CASE
WHEN NUM.N IS NULL
THEN @amt
ELSE
SUBSTRING(RTRIM(@amt),1, LEN(@amt) - 1) + Num.N
END
) TP
OUTER APPLY(
SELECT Y = CASE
WHEN NEG.N = 0
THEN (CAST(TP.Amt AS NUMERIC) / 100)
WHEN NEG.N = 1
THEN (CAST (TP.Amt AS NUMERIC) /100) * -1
END
) RET
) ;
GOVoici la version de la fonction scalaire dont j'ai hérité, si quelqu'un est intéressé:
CREATE FUNCTION dbo.ConvertAmountVerified
(
@amt VARCHAR(50)
)
RETURNS NUMERIC (18,3)
AS
BEGIN
-- Declare the return variable here
DECLARE @Amount NUMERIC(18, 3);
DECLARE @TempAmount VARCHAR (50);
DECLARE @Num VARCHAR(1);
DECLARE @LastChar VARCHAR(1);
DECLARE @Negative BIT ;
-- Get Last Character
SELECT @LastChar = RIGHT(RTRIM(@amt), 1) ;
SELECT @Num = CASE @LastChar collate latin1_general_cs_as
WHEN '{' THEN '0'
WHEN 'A' THEN '1'
WHEN 'B' THEN '2'
WHEN 'C' THEN '3'
WHEN 'D' THEN '4'
WHEN 'E' THEN '5'
WHEN 'F' THEN '6'
WHEN 'G' THEN '7'
WHEN 'H' THEN '8'
WHEN 'I' THEN '9'
WHEN '}' THEN '0'
WHEN 'J' THEN '1'
WHEN 'K' THEN '2'
WHEN 'L' THEN '3'
WHEN 'M' THEN '4'
WHEN 'N' THEN '5'
WHEN 'O' THEN '6'
WHEN 'P' THEN '7'
WHEN 'Q' THEN '8'
WHEN 'R' THEN '9'
---ASCII
WHEN 'p' Then '0'
WHEN 'q' Then '1'
WHEN 'r' Then '2'
WHEN 's' Then '3'
WHEN 't' Then '4'
WHEN 'u' Then '5'
WHEN 'v' Then '6'
WHEN 'w' Then '7'
WHEN 'x' Then '8'
WHEN 'y' Then '9'
ELSE ''
END
SELECT @Negative = CASE @LastChar collate latin1_general_cs_as
WHEN '{' THEN 0
WHEN 'A' THEN 0
WHEN 'B' THEN 0
WHEN 'C' THEN 0
WHEN 'D' THEN 0
WHEN 'E' THEN 0
WHEN 'F' THEN 0
WHEN 'G' THEN 0
WHEN 'H' THEN 0
WHEN 'I' THEN 0
WHEN '}' THEN 1
WHEN 'J' THEN 1
WHEN 'K' THEN 1
WHEN 'L' THEN 1
WHEN 'M' THEN 1
WHEN 'N' THEN 1
WHEN 'O' THEN 1
WHEN 'P' THEN 1
WHEN 'Q' THEN 1
WHEN 'R' THEN 1
---ASCII
WHEN 'p' Then '1'
WHEN 'q' Then '1'
WHEN 'r' Then '1'
WHEN 's' Then '1'
WHEN 't' Then '1'
WHEN 'u' Then '1'
WHEN 'v' Then '1'
WHEN 'w' Then '1'
WHEN 'x' Then '1'
WHEN 'y' Then '1'
ELSE 0
END
-- Add the T-SQL statements to compute the return value here
if (@Num ='')
begin
SELECT @TempAmount=@amt;
end
else
begin
SELECT @TempAmount = SUBSTRING(RTRIM(@amt),1, LEN(@amt) - 1) + @Num;
end
SELECT @Amount = CASE @Negative
WHEN 0 THEN (CAST(@TempAmount AS NUMERIC) / 100)
WHEN 1 THEN (CAST (@TempAmount AS NUMERIC) /100) * -1
END ;
-- Return the result of the function
RETURN @Amount
ENDExemples de données de test:
SELECT dbo.ConvertAmountVerified('00064170') -- 641.700
SELECT * FROM dbo.ConvertAmountVerified_TVF('00064170') -- 641.700
SELECT dbo.ConvertAmountVerified('00057600A') -- 5760.010
SELECT * FROM dbo.ConvertAmountVerified_TVF('00057600A') -- 5760.010
SELECT dbo.ConvertAmountVerified('00059224y') -- -5922.490
SELECT * FROM dbo.ConvertAmountVerified_TVF('00059224y') -- -5922.490