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Andrew Pallant

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How to use SQL to Extract a Number from a String

Physical Link: How to use SQL to Extract a Number from a String


Recently I had a need to extract the number from a string in the database.  The string would be something like ‘Monitor 16″‘ or “16 inch Monitor”.   I would need to get the size for various reasons including fees and reports, but no real good way of doing it.  I have come up with the following Scalar SQL Function to do this very job.

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:		Andrew Pallant
-- Create date: August 27, 2013
-- Description:	Get Numeric Value Prior to a String within a String.
-- =============================================
CREATE FUNCTION f_read_num_before_some_string 
(
	-- Add the parameters for the function here
	@stringValue varchar(max),
	@search varchar(max)
)
RETURNS varchar(100)
AS
BEGIN
	-- Declare the return variable here
DECLARE @intval as varchar(100)   -- Value to be returned
DECLARE @RECORDINGVALUE bit       -- Flag to indicate the recording of the value to be returned
declare @newvalue as varchar(100) -- Working String Value

-- Set Defaults
set @newvalue = ''                
set @RECORDINGVALUE = 0
set @intval = null

-- Start Looping and Building	
	IF len(isnull(@stringValue,'')) > 0 BEGIN
		declare @startIndex as int
		set @startIndex = CHARINDEX(@search,@stringValue)

		declare @counter int
		set @counter = @startIndex

		WHILE @counter > 0 BEGIN
			declare @temp as varchar(1)
			set @temp = substring(@stringValue,@counter,1)
			if @temp = ' ' and LEN(@newvalue)> 0 BEGIN
				-- STOP - Drop and Roll
				set @counter = -1
			END 

			-- If we have a space - do work!
			IF @temp <> ' ' BEGIN
				IF @RECORDINGVALUE = 1 and isnumeric(@temp) = 0 BEGIN
					set @counter = -1
					-- STOP - Drop and Roll
				END ELSE IF isnumeric(@temp) = 1 BEGIN
					set @RECORDINGVALUE = 1

					-- Build Return Value
					set @newvalue = @temp + @newvalue;
				END
			END 

			set @counter = @counter - 1
		END
	END

	IF @newvalue = '' BEGIN SET @newvalue = '0' END

	-- Return the result of the function
	RETURN @newvalue
END
GO

The post How to use SQL to Extract a Number from a String appeared first on Software Developer In London.

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Categories: Developement, How To, SQL, Numbers


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