Extract Numbers From String In SQL Server

I was looking for options to retrieve numbers from an alpha numeric string. I could find code to remove alpha characters from the string leaving the numeric characters forming one large number. However, my requirement is to extract the number sets and separate them with commas. i.e. if there is an alpha numeric string abc123def456ghi789 the numbers should be segregated as 123,456,789. So, I wrote a small user defined function to extract the numbers in sets.

Function To Extract Numbers From String

CREATE FUNCTION [dbo].[mtb_GetNumbers] 
(
	@stInput VARCHAR(max)
)
RETURNS VARCHAR(max)
AS
BEGIN

	SET @stInput = REPLACE(@stInput,',','')
	
	DECLARE @intAlpha INT
	DECLARE @intNumber INT

	SET @intAlpha = PATINDEX('%[^0-9,]%', @stInput)
	SET @intNumber = PATINDEX('%[0-9,]%', @stInput)

	IF @stInput IS NULL OR @intNumber = 0
		RETURN '';

	WHILE @intAlpha > 0 
	BEGIN
		IF (@intAlpha > @intNumber)
		BEGIN
			SET @intNumber = PATINDEX('%[0-9,]%', SUBSTRING(@stInput, @intAlpha, LEN(@stInput)) )
			SELECT @intNumber = CASE WHEN @intNumber = 0 THEN LEN(@stInput) ELSE @intNumber END
		END

		SET @stInput = STUFF(@stInput, @intAlpha, @intNumber - 1,',' );
			
		SET @intAlpha = PATINDEX('%[^0-9,]%', @stInput )
		SET @intNumber = PATINDEX('%[0-9,]%', SUBSTRING(@stInput, @intAlpha, LEN(@stInput)) )
		SELECT @intNumber = CASE WHEN @intNumber = 0 THEN LEN(@stInput) ELSE @intNumber END
	END
	

	IF (RIGHT(@stInput, 1) = ',')
		SET @stInput = LEFT(@stInput, LEN(@stInput) - 1)

	IF (LEFT(@stInput, 1) = ',')
		SET @stInput = RIGHT(@stInput, LEN(@stInput) - 1)

	RETURN ISNULL(@stInput,0)
END
GO

Testing The Function

/* Testing the function with alpha numeric strings */
SELECT '1a2b3c',  dbo.mtb_GetNumbers('1a2b3c');
SELECT '123abc',  dbo.mtb_GetNumbers('123abc');
SELECT 'abc123',  dbo.mtb_GetNumbers('abc123');
SELECT 'a123b',  dbo.mtb_GetNumbers('a123b');
SELECT '1abc2',  dbo.mtb_GetNumbers('1abc2');
SELECT '123abc123abc',  dbo.mtb_GetNumbers('123abc123abc');
SELECT '',  dbo.mtb_GetNumbers('');
SELECT 'NonNumeric', dbo.mtb_GetNumbers('NonNumeric');
SELECT 'NULL', dbo.mtb_GetNumbers(NULL);
SELECT 'Azure4234SQL232Data333Warehouse23and0Parallel,Data43434Warehouse',  dbo.mtb_GetNumbers('Azure4234SQL232Data333Warehouse23and0Parallel,Data43434Warehouse');
GO

Result

Now we get the numbers as a string segregated with commas. If you want to split this delimited numbers, use STRING_SPLIT() in SQL Server 2016  or other options in older versions as explained here.

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