try_cast - Try_Convert para SQL Server 2008 R2

try convert sql server 2008

Question

Estoy usando SQL Server 2008 R2 y tengo una columna VARCHAR que quiero convertir a DECIMAL(28,10) usando CONVERT . Pero muchas de esas filas están mal formateadas, por lo que no es posible analizarlas en un número. En ese caso, solo quiero omitir esos al establecer el resultado en 0 o NULO.

Sé que hay una nueva declaración en SQL Server 2012 ( TRY_CONVERT() ) que sería útil.

¿Es esto posible en 2008 o debo esperar hasta que actualicemos a la próxima versión de SQL 2012?

EDITAR

Desafortunadamente ISNUMERIC() no es confiable en este caso. Lo intenté

ISNUMERIC(myCol) = 1

Esto devuelve verdadero para las filas que CONVERT no puede convertir a DECIMAL .

Answer 1

Al usar XML en SQL Server puede tratar de convertir a un tipo de datos y recibir valores nulos donde falla el lanzamiento.

declare @T table
(
  Col varchar(50)
)

insert into @T values
(''1''),
(''1.1''),
(''1,1''),
(''1a'')

select cast('''' as xml).value(''sql:column("Col") cast as xs:decimal ?'', 
                             ''decimal(28,10)'') as Col
from @T

Resultado:

Col
-------------
1.0000000000
1.1000000000
NULL
NULL

Answer 2

Como se trata de un cambio permanente, lo haría como un proceso de dos pasos: primero, elimine el texto no válido y luego convierta la columna.

Para eliminar el texto no válido, haría algo como:

UPDATE [Table]
SET [Column] = NULL
WHERE [Column] LIKE ''%[^0-9.]%'' or
LEN([Column]) - LEN(REPLACE([Column],''.'','''')) > 1 or
LEN([Column]) > 28

Una vez hecho esto, todo lo que queda debe ser convertible simplemente cambiando la definición de columna

ALTER TABLE [Table] ALTER COLUMN [Column] decimal(28,10)

Answer 3

Escribí una función escalar útil para simular la función TRY_CAST de SQL Server 2012 en SQL Server 2008.

dbo.TRY_CAST(Expression, Data_Type, ReturnValueIfErrorCast)

Las dos principales diferencias con TRY_CAST Function para SQL Server 2012 son que debe pasar 3 parámetros y además debe realizar un CONVERT o CAST explícito en el campo. Sin embargo, sigue siendo muy útil porque le permite devolver un valor predeterminado si CAST no se realiza correctamente.

CÓDIGO DE FUNCIÓN:

DECLARE @strSQL NVARCHAR(1000)
IF NOT EXISTS (SELECT * FROM dbo.sysobjects WHERE id = OBJECT_ID(N''[dbo].[TRY_CAST]''))
    BEGIN
        SET @strSQL = ''CREATE FUNCTION [dbo].[TRY_CAST] () RETURNS INT AS BEGIN RETURN 0 END''
        EXEC sys.sp_executesql @strSQL
    END

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

/*
------------------------------------------------------------------------------------------------------------------------
    Description:    
                    Syntax 
                    ---------------
                    dbo.TRY_CAST(Expression, Data_Type, ReturnValueIfErrorCast)

                    +---------------------------+-----------------------+
                    |   Expression              |   VARCHAR(8000)       |
                    +---------------------------+-----------------------+
                    |   Data_Type               |   VARCHAR(8000)       |
                    +---------------------------+-----------------------+
                    |   ReturnValueIfErrorCast  |   SQL_VARIANT = NULL  |
                    +---------------------------+-----------------------+


                    Arguments
                    ---------------
                    expression
                    The value to be cast. Any valid expression.

                    Data_Type
                    The data type into which to cast expression.

                    ReturnValueIfErrorCast
                    Value returned if cast fails or is not supported. Required. Set the DEFAULT value by default.


                    Return Type
                    ----------------
                    Returns value cast to SQL_VARIANT type if the cast succeeds; otherwise, returns null if the parameter @pReturnValueIfErrorCast is set to DEFAULT, 
                    or that the user indicates.


                    Remarks
                    ----------------
                    dbo.TRY_CAST function simulates the TRY_CAST function reserved of SQL SERVER 2012 for using in SQL SERVER 2008. 
                    dbo.TRY_CAST function takes the value passed to it and tries to convert it to the specified Data_Type. 
                    If the cast succeeds, dbo.TRY_CAST returns the value as SQL_VARIANT type; if the cast doesn´t succees, null is returned if the parameter @pReturnValueIfErrorCast is set to DEFAULT. 
                    If the Data_Type is unsupported will return @pReturnValueIfErrorCast.
                    dbo.TRY_CAST function requires user make an explicit CAST or CONVERT in ANY statements.
                    This version of dbo.TRY_CAST only supports CAST for INT, DATE, NUMERIC and BIT types.


                    Examples
                    ====================================================================================================

                    --A. Test TRY_CAST function returns null

                        SELECT   
                            CASE WHEN dbo.TRY_CAST(''6666666166666212'', ''INT'', DEFAULT) IS NULL   
                            THEN ''Cast failed''  
                            ELSE ''Cast succeeded''  
                        END AS Result; 

                    GO

                    --B. Error Cast With User Value

                        SELECT   
                            dbo.TRY_CAST(''2147483648'', ''INT'', DEFAULT) AS [Error Cast With DEFAULT],
                            dbo.TRY_CAST(''2147483648'', ''INT'', -1) AS [Error Cast With User Value],
                            dbo.TRY_CAST(''2147483648'', ''INT'', NULL) AS [Error Cast With User NULL Value]; 

                        GO 

                    --C. Additional CAST or CONVERT required in any assignment statement

                        DECLARE @IntegerVariable AS INT

                        SET @IntegerVariable = CAST(dbo.TRY_CAST(123, ''INT'', DEFAULT) AS INT)

                        SELECT @IntegerVariable

                        GO 

                        IF OBJECT_ID(''tempdb..#temp'') IS NOT NULL
                            DROP TABLE #temp

                        CREATE TABLE #temp (
                            Id INT IDENTITY
                            , FieldNumeric NUMERIC(3, 1)
                            )

                        INSERT INTO dbo.#temp (FieldNumeric)
                        SELECT CAST(dbo.TRY_CAST(12.3, ''NUMERIC(3,1)'', 0) AS NUMERIC(3, 1));--Need explicit CAST on INSERT statements

                        SELECT *
                        FROM #temp

                        DROP TABLE #temp

                        GO 

                    --D. Supports CAST for INT, DATE, NUMERIC and BIT types.

                        SELECT dbo.TRY_CAST(2147483648, ''INT'', 0) AS [Cast failed]
                            , dbo.TRY_CAST(2147483647, ''INT'', 0) AS [Cast succeeded]
                            , SQL_VARIANT_PROPERTY(dbo.TRY_CAST(212, ''INT'', 0), ''BaseType'') AS [BaseType];

                        SELECT dbo.TRY_CAST(''AAAA0101'', ''DATE'', DEFAULT) AS [Cast failed]
                            , dbo.TRY_CAST(''20160101'', ''DATE'', DEFAULT) AS [Cast succeeded]
                            , SQL_VARIANT_PROPERTY(dbo.TRY_CAST(''2016-01-01'', ''DATE'', DEFAULT), ''BaseType'') AS [BaseType];

                        SELECT dbo.TRY_CAST(1.23, ''NUMERIC(3,1)'', DEFAULT) AS [Cast failed]
                            , dbo.TRY_CAST(12.3, ''NUMERIC(3,1)'', DEFAULT) AS [Cast succeeded]
                            , SQL_VARIANT_PROPERTY(dbo.TRY_CAST(12.3, ''NUMERIC(3,1)'', DEFAULT), ''BaseType'') AS [BaseType];

                        SELECT dbo.TRY_CAST(''A'', ''BIT'', DEFAULT) AS [Cast failed]
                            , dbo.TRY_CAST(1, ''BIT'', DEFAULT) AS [Cast succeeded]
                            , SQL_VARIANT_PROPERTY(dbo.TRY_CAST(''123'', ''BIT'', DEFAULT), ''BaseType'') AS [BaseType];

                        GO 

                    --E. B. TRY_CAST return NULL on unsupported data_types

                        SELECT dbo.TRY_CAST(4, ''xml'', DEFAULT) AS [unsupported];  

                        GO  

                    ====================================================================================================

------------------------------------------------------------------------------------------------------------------------
    Responsible:    Javier Pardo 
    Date:           diciembre 29/2016
    WB tests:       Javier Pardo 
------------------------------------------------------------------------------------------------------------------------
    Update by:      Javier Eduardo Pardo Moreno 
    Date:           febrero 16/2017
    Id update:      JEPM20170216
    Description:    Fix  ISNUMERIC function makes it unreliable. SELECT dbo.TRY_CAST(''+'', ''INT'', 0) will yield Msg 8114, 
                    Level 16, State 5, Line 16 Error converting data type varchar to float.
                    ISNUMERIC() function treats few more characters as numeric, like: – (minus), + (plus), $ (dollar), / (back slash), (.)dot and (,)comma
                    Collaborator aperiooculus (http://.com/users/3083382/aperiooculus )

                    Fix dbo.TRY_CAST(''2013/09/20'', ''datetime'', DEFAULT) for supporting DATETIME format

    WB tests:       Javier Pardo

------------------------------------------------------------------------------------------------------------------------
*/

ALTER FUNCTION dbo.TRY_CAST
(
    @pExpression AS VARCHAR(8000),
    @pData_Type AS VARCHAR(8000),
    @pReturnValueIfErrorCast AS SQL_VARIANT = NULL
)
RETURNS SQL_VARIANT
AS
BEGIN
    --------------------------------------------------------------------------------
    --  INT 
    --------------------------------------------------------------------------------

    IF @pData_Type = ''INT''
    BEGIN
        IF ISNUMERIC(@pExpression) = 1 AND @pExpression NOT IN (''-'',''+'',''$'',''.'','','',''/')    --JEPM20170216
        BEGIN
            DECLARE @pExpressionINT AS FLOAT = CAST(@pExpression AS FLOAT)

            IF @pExpressionINT BETWEEN - 2147483648.0 AND 2147483647.0
            BEGIN
                RETURN CAST(@pExpressionINT as INT)
            END
            ELSE
            BEGIN
                RETURN @pReturnValueIfErrorCast
            END --FIN IF @pExpressionINT BETWEEN - 2147483648.0 AND 2147483647.0
        END
        ELSE
        BEGIN
            RETURN @pReturnValueIfErrorCast
        END -- FIN IF ISNUMERIC(@pExpression) = 1
    END -- FIN IF @pData_Type = ''INT''

    --------------------------------------------------------------------------------
    --  DATE    
    --------------------------------------------------------------------------------

    IF @pData_Type IN (''DATE'',''DATETIME'')
    BEGIN
        IF ISDATE(@pExpression) = 1
        BEGIN

            DECLARE @pExpressionDATE AS DATETIME = cast(@pExpression AS DATETIME)

            IF @pData_Type = ''DATE''
            BEGIN
                RETURN cast(@pExpressionDATE as DATE)
            END

            IF @pData_Type = ''DATETIME''
            BEGIN
                RETURN cast(@pExpressionDATE as DATETIME)
            END

        END
        ELSE 
        BEGIN

            DECLARE @pExpressionDATEReplaced AS VARCHAR(50) = REPLACE(REPLACE(REPLACE(@pExpression,''/',''''),''/'',''''),''-'','''')

            IF ISDATE(@pExpressionDATEReplaced) = 1
            BEGIN
                IF @pData_Type = ''DATE''
                BEGIN
                    RETURN cast(@pExpressionDATEReplaced as DATE)
                END

                IF @pData_Type = ''DATETIME''
                BEGIN
                    RETURN cast(@pExpressionDATEReplaced as DATETIME)
                END

            END
            ELSE
            BEGIN
                RETURN @pReturnValueIfErrorCast
            END
        END --FIN IF ISDATE(@pExpression) = 1
    END --FIN IF @pData_Type = ''DATE''

    --------------------------------------------------------------------------------
    --  NUMERIC 
    --------------------------------------------------------------------------------

    IF @pData_Type LIKE ''NUMERIC%''
    BEGIN

        IF ISNUMERIC(@pExpression) = 1
        BEGIN

            DECLARE @TotalDigitsOfType AS INT = SUBSTRING(@pData_Type,CHARINDEX(''('',@pData_Type)+1,  CHARINDEX('','',@pData_Type) - CHARINDEX(''('',@pData_Type) - 1)
                , @TotalDecimalsOfType AS INT = SUBSTRING(@pData_Type,CHARINDEX('','',@pData_Type)+1,  CHARINDEX('')'',@pData_Type) - CHARINDEX('','',@pData_Type) - 1)
                , @TotalDigitsOfValue AS INT 
                , @TotalDecimalsOfValue AS INT 
                , @TotalWholeDigitsOfType AS INT 
                , @TotalWholeDigitsOfValue AS INT 

            SET @pExpression = REPLACE(@pExpression, '','',''.'')

            SET @TotalDigitsOfValue = LEN(REPLACE(@pExpression, ''.'',''''))
            SET @TotalDecimalsOfValue = CASE Charindex(''.'', @pExpression)
                                        WHEN 0
                                            THEN 0
                                        ELSE Len(Cast(Cast(Reverse(CONVERT(VARCHAR(50), @pExpression, 128)) AS FLOAT) AS BIGINT))
                                        END 
            SET @TotalWholeDigitsOfType = @TotalDigitsOfType - @TotalDecimalsOfType
            SET @TotalWholeDigitsOfValue = @TotalDigitsOfValue - @TotalDecimalsOfValue

            -- The total digits can not be greater than the p part of NUMERIC (p, s)
            -- The total of decimals can not be greater than the part s of NUMERIC (p, s)
            -- The total digits of the whole part can not be greater than the subtraction between p and s
            IF (@TotalDigitsOfValue <= @TotalDigitsOfType) AND (@TotalDecimalsOfValue <= @TotalDecimalsOfType) AND (@TotalWholeDigitsOfValue <= @TotalWholeDigitsOfType)
            BEGIN
                DECLARE @pExpressionNUMERIC AS FLOAT
                SET @pExpressionNUMERIC = CAST (ROUND(@pExpression, @TotalDecimalsOfValue) AS FLOAT) 

                RETURN @pExpressionNUMERIC --Returns type FLOAT
            END 
            else
            BEGIN
                RETURN @pReturnValueIfErrorCast
            END-- FIN IF (@TotalDigitisOfValue <= @TotalDigits) AND (@TotalDecimalsOfValue <= @TotalDecimals) 

        END
        ELSE 
        BEGIN
            RETURN @pReturnValueIfErrorCast
        END --FIN IF ISNUMERIC(@pExpression) = 1
    END --IF @pData_Type LIKE ''NUMERIC%''

    --------------------------------------------------------------------------------
    --  BIT 
    --------------------------------------------------------------------------------

    IF @pData_Type LIKE ''BIT''
    BEGIN
        IF ISNUMERIC(@pExpression) = 1
        BEGIN
            RETURN CAST(@pExpression AS BIT) 
        END
        ELSE 
        BEGIN
            RETURN @pReturnValueIfErrorCast
        END --FIN IF ISNUMERIC(@pExpression) = 1
    END --IF @pData_Type LIKE ''BIT''


    --------------------------------------------------------------------------------
    --  FLOAT   
    --------------------------------------------------------------------------------

    IF @pData_Type LIKE ''FLOAT''
    BEGIN
        IF ISNUMERIC(REPLACE(REPLACE(@pExpression, CHAR(13), ''''), CHAR(10), '''')) = 1
        BEGIN

            RETURN CAST(@pExpression AS FLOAT) 
        END
        ELSE 
        BEGIN

            IF REPLACE(@pExpression, CHAR(13), '''') = '''' --Only white spaces are replaced, not new lines
            BEGIN
                RETURN 0
            END
            ELSE 
            BEGIN
                RETURN @pReturnValueIfErrorCast
            END --IF REPLACE(@pExpression, CHAR(13), '''') = '''' 

        END --FIN IF ISNUMERIC(@pExpression) = 1
    END --IF @pData_Type LIKE ''FLOAT''

    --------------------------------------------------------------------------------
    --  Any other unsupported data type will return NULL or the value assigned by the user to @pReturnValueIfErrorCast  
    --------------------------------------------------------------------------------

    RETURN @pReturnValueIfErrorCast



END

Por ahora, solo admite los tipos de datos INT, DATE, DATETIME, NUMERIC, BIT y FLOAT . Puede encontrar la última versión de este código en el siguiente enlace a continuación y nos ayudamos mutuamente para mejorarlo. Función TRY_CAST para SQL Server 2008 https://gist.github.com/jotapardo/800881eba8c5072eb8d99ce6eb74c8bb

Answer 4

Finalmente descubrí cómo hacerlo con la ayuda de SO y Google.

La declaración de actualización:

UPDATE PriceTerm 
SET PercentAddition = CONVERT(decimal(28,10), RTRIM(LTRIM(REPLACE(REPLACE(REPLACE(AdditionalDescription,''%'',''''), '','',''.''), ''&'', '''')))) 
WHERE AdditionalDescription LIKE ''%[%]%'' AND
dbo.isreallynumeric(RTRIM(LTRIM(REPLACE(REPLACE(REPLACE(AdditionalDescription,''%'',''''), '','',''.''), ''&'', '''')))) = 1 AND
PercentAddition = 0

Primero busco% char como la mayoría de las veces que se utiliza como marcador para el valor porcentual. Pero también hay otros usos al azar. Resultó que ISNUMERIC no era confiable en mi caso.

Lo que realmente hace la diferencia es que la llamada al procedimiento almacenado es realinemónica desde here .

Asi que

CREATE FUNCTION dbo.isReallyNumeric  
(  
    @num VARCHAR(64)  
)  
RETURNS BIT  
BEGIN  
    IF LEFT(@num, 1) = ''-''  
        SET @num = SUBSTRING(@num, 2, LEN(@num))  

    DECLARE @pos TINYINT  

    SET @pos = 1 + LEN(@num) - CHARINDEX(''.'', REVERSE(@num))  

    RETURN CASE  
    WHEN PATINDEX(''%[^0-9.-]%'', @num) = 0  
        AND @num NOT IN (''.'', ''-'', ''+'', ''^'') 
        AND LEN(@num)>0  
        AND @num NOT LIKE ''%-%'' 
        AND  
        (  
            ((@pos = LEN(@num)+1)  
            OR @pos = CHARINDEX(''.'', @num))  
        )  
    THEN  
        1  
    ELSE  
    0  
    END  
END  
GO 

Answer 5

Prefiero soluciones simples e hice un SP como el siguiente.

CREATE PROC TRY_CAST 
(   
    @valueToBeParsed VARCHAR(64), @parsedValue INT OUTPUT
)
AS
BEGIN
    BEGIN TRY
        SELECT @parsedValue = cast(@valueToBeParsed as int)
    END TRY
    BEGIN CATCH
    SET @parsedValue = null
    END CATCH
END
GO

y lo usé como siguiendo

DECLARE @val int
EXEC TRY_CAST ''1w'', @val out
select @val

Answer 6

Puede escribir su propio analizador personalizado en C # y usar SQLCLR, usando, por ejemplo, Decimal.Parse() . No intente utilizar ISNUMERIC , es notoriamente incorrect (devuelve TRUE para las cadenas que no pueden CAST).

Answer 7

SQL SERVER 2008 R2 tiene una función TRY_CAST pero si configura su DB con compatibilidad con 2005, encontró que SQL SERVER no lo reconoce.

Utilicé la función que crea pero renombre TRY_CAST2 porque SS en este caso reconoció la función.