Question

When we have a column that will store a username that will only accept letters and numbers we always do validation on this input field using javascript or even server validation from code .. but i want to know if is there any way that can allow me make this validation on the Table column itself even some one try to enter data from any place it don’t accept and throw exception ?

Answer 1

You could probably do something with a check constraint on the column. T-SQL doesn’t natively have a regex function, although LIKE (as mentioned by AakashM below) is smart enough to do this. To get a full regex capability you can use CLR integration to wrap the .Net Regex function and then wrap the regex with a UDF and use the check constraint to invoke the function to evaluate the contents of the column.

Here’s another article about using CLR UDFs for regex matching in T-SQL.