How to Remove alpha characters from string in SQL SERVER.

First of all create a function and then after use this function when you need just number from string.

CREATE FUNCTION [dbo].[RemoveAlphaCharacters]
    (
      @string2number VARCHAR(200)
    )
RETURNS VARCHAR(200)
AS
    BEGIN
        DECLARE @c INT
        DECLARE @num VARCHAR(200)
        SET @num = ''
        DECLARE @txtCurrent CHAR(1)
        SET @c = 1
        WHILE @c <= LEN(@string2number)
            BEGIN
                SET @txtCurrent = SUBSTRING(@string2number, @c, 1)
                IF ASCII(@txtCurrent) BETWEEN 48 AND 57
                    SET @num = @num + @txtCurrent
                SET @c = @c + 1
            END
        RETURN @num
    END


SELECT dbo.RemoveAlphaCharacters('nikhil1711sangani')

OUTPUT : 1711