I have a user defined function called Sync_CheckData under Scalar-valued functions in Microsoft SQL Server. What it actually does is to check the quantity of issued product and balance quantity are the same. If something is wrong, returns an ErrorStr nvarchar(255). Output Example: Balance Stock Error for Product ID : 4 From the above string, I want to get 4 so that later on I can SELECT the rows which is giving errors by using WHERE clause (WHERE Product_ID = 4). Which SQL function can I use to get the substring?