有沒有辦法調用Sql Server函數轉換/拋出而不讓它們拋出異常？將varchar值轉換爲int，而不會在輸入錯誤時拋出異常
基本上，我有一列包含字母數字數據，我從字段中提取值，我想將數據顯示爲整數值。有時候提取的數據不是數字，在這種情況下，我希望Sql Server跳過該行（返回null或0）。
眼下SQL SELECT語句失敗，出現「轉換爲nvarchar值時，轉換失敗‘爲XXXXX’爲int數據類型。
我想要的是類似於C＃的int.TryParse東西。
建議？
select case when isnumeric(YourColumn + '.0e0') = 1
then cast(YourColumn as int)
else NULL
end /* case */
from YourTable
在SQL Server 2012中有功能這
檢查，以確保它是一個整數，你在那裏使用下面的函數
/****** Object: UserDefinedFunction [dbo].[IsInteger] Script Date: 04/10/2013 09:46:19 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE Function [dbo].[IsInteger](@Value VarChar(50))
Returns Bit
As
Begin
DECLARE @is_int bit
SELECT @is_int = CASE
WHEN @Value IS NULL THEN 0
WHEN @Value = ' ' THEN 0
WHEN ISNUMERIC(@Value + '.0e0') = 0 THEN 0
WHEN @Value LIKE '%\[^-+ 0-9\]%' THEN 0
WHEN CAST(@Value AS NUMERIC(38, 0))
NOT BETWEEN -2147483648. AND 2147483647. THEN 0
ELSE 1
END
return @is_int
End
GO
然後做鑄造前where子句中dbo.IsInteger（yourstring）
這種嘗試我創建的功能
官方鏈接： https://gist.github.com/jotapardo/800881eba8c5072eb8d99ce6eb74c8bb
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
------------------------------------------------------------------------------------------------------------------------
*/
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
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 = 'DATE'
BEGIN
IF ISDATE(@pExpression) = 1
BEGIN
DECLARE @pExpressionDATE AS DATE = cast(@pExpression AS DATE)
RETURN cast(@pExpressionDATE as DATE)
END
ELSE
BEGIN
RETURN @pReturnValueIfErrorCast
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
而且試試這個：
SELECT dbo.TRY_CAST(YourColumn, 'INT', NULL)
目前只支持數據類型INT，DATE，數字，BIT和浮
我希望你覺得它有用。
這就是爲什麼你正確的數據類型。 – 2011-02-07 17:21:18