The below works correctly and filters my gridview based on the text entered in my textbox.
When no text is entered into my textbox I get no results and cannot unders
Instead of coalesce you may have a if block which checks if the @search parameter is empty or not as shown below..
if @search is not empty
SELECT [table].[column]
FROM [table]
WHERE [table].[column] LIKE '%' + @Search + '%' OR COALESCE(@Search,'') = ''
else
SELECT [table].[column]
FROM [table]
WHERE [table].[column]