Query to get only numbers from a string

I have data like this:

string 1: 003Preliminary Examination Plan   
string 2: Coordination005  
string 3: Balance1000sheet

The output I expect is

string 1: 003
string 2: 005
string 3: 1000

And I want to implement it in SQL.

First create this UDF

CREATE FUNCTION dbo.udf_GetNumeric
(
  @strAlphaNumeric VARCHAR(256)
)
RETURNS VARCHAR(256)
AS
BEGIN
  DECLARE @intAlpha INT
  SET @intAlpha = PATINDEX('%[^0-9]%', @strAlphaNumeric)
  BEGIN
    WHILE @intAlpha > 0
    BEGIN
      SET @strAlphaNumeric = STUFF(@strAlphaNumeric, @intAlpha, 1, '' )
      SET @intAlpha = PATINDEX('%[^0-9]%', @strAlphaNumeric )
    END
  END
  RETURN LEN(COALESCE(TRIM(CAST(ISNULL(@strAlphaNumeric, 0) AS INT)),0))>0 then COALESCE(TRIM(CAST(ISNULL(@strAlphaNumeric, 0) AS INT)),0) else 0 end
END
GO

Now use the function as

SELECT dbo.udf_GetNumeric(column_name) 
from table_name

SQL FIDDLE

I hope this solved your problem.

Reference

4/10/23 - Modified Return Statement based on comments