As others have said - look into securing your app in other ways.
Take this query for example: stackoverflow.com/questions/1446821/how-to-get-ne… select * from foo where id = (select min(id) from foo where id > 4)
That query technically wouldn't care if it was querying an INT or Varchar (replace the 4 with a string) - it'll pull the next record based on whats passed in. > can still apply to strings; they'll just be sorted alphabetically, not numerically.
Your goal is to stop (select min(id) from foo where id > 4) from being injected into the app. Any (all) input fields when using SQL should be sanitized.