What is the simplest way to get the same output in SQL Server 2008?
SQLServer 2012 :
select
try_parse(Isnull('123.66',0) as float) as a ,
try_parse(Isnull('.',0) as float) as b
Result
a b
------------
123.66 NULL
SQLServer 2008 : ?
TRY_PARSE does two things - parse text using a specific culture and return NULL if the cast fails. In SQL Server 2008 you can emulate part of this functionality using the ISNUMERIC function, as shown here:
select
CASE
WHEN ISNUMERIC(@input)=1 and LEFT(@input,1) LIKE'[0-9]' THEN
CAST(@input as float)
ELSE
NULL
END,
ISNUMERIC will return 1 even for . or '.5' though, causing the cast to fail. This is covered by the second check LEFT(@input,1) LIKE'[0-9]'
You can create a scalar function so you don't have to type all this each time you want to cast a value:
CREATE FUNCTION try_parse_float(@input varchar(20))
returns float
AS
begin
declare @result float;
select @result=CASE
WHEN ISNUMERIC(@input)=1 and LEFT(@input,1) LIKE'[0-9]'
THEN CAST(@input as float)
ELSE NULL
END;
return @result;
end
So you can write
SELECT dbo.try_parse_float('123,4'), try_parse_float('.')
----- ----
123.4 NULL
EDIT
The safest and fastest option would be simply to avoid storing numeric values as text in the database, making sure the data is parsed during loading instead. For example, .NET and OLEDB providers can parse "123-" to -123 while T-SQL can't.
It's also much easier to handle custom formats during loading, eg with a float.TryParseExact call before saving form data to the database, or with a C# Script component in an SSIS ETL script.
I wrote a useful scalar function to simulate the TRY_CAST function of SQL SERVER 2012 in SQL Server 2008.
dbo.TRY_CAST(Expression, Data_Type, ReturnValueIfErrorCast)
The two main differences with TRY_CAST Function fo SQL Server 2012 are that you must pass 3 parameters and you must additionally perform an explicit CONVERT or CAST to the field. However, it is still very useful because it allows you to return a default value if CAST is not performed correctly.
FUNCTION CODE:
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
For now only supports the data types INT, DATE, NUMERIC, BIT and FLOAT. You can find the last versión of this code in the next link below and we help each other to improve it. TRY_CAST Function for SQL Server 2008 https://gist.github.com/jotapardo/800881eba8c5072eb8d99ce6eb74c8bb
You can use this codesnippet which should do the thing your looking for. It shouldn't be a big deal for you to add this to a select on a bigger table. Just replace the variable with the code column.
Here is the example:
DECLARE @string nvarchar(255)
SET @string = 'Hali€hHalo'
SELECT Substring(
@string,
PATINDEX('%[0-9.]%',@string),
PATINDEX('%[^0-9.]%',
Substring(
@string,
PATINDEX(
'%[0-9.]%',
@string
),
LEN(@string)
)
)-1
)
GO
Result: Empty string, but this can be replaced with a CASE WHEN ... IS NULL THEN NULL ELSE ... END if needed to a NULL.
The The same thing with a variable with a number.
DECLARE @string nvarchar(255)
SET @string = 'Hali123.10€hHalo'
SELECT Substring(
@string,
PATINDEX('%[0-9.]%',@string),
PATINDEX('%[^0-9.]%',
Substring(
@string,
PATINDEX(
'%[0-9.]%',
@string
),
LEN(@string)
)
)-1
)
GO
Results in: 123.10
Best regards, Ionic
