sql select with null values

Question

I have SP that selects data from a table with two columns like this

@param1 text,
@param2 text
Select * from tablle1 where field1 like @param1 and field2 like @param2

However , because sometimes Filed2 is null i had to do this , otherwise the query returned nothing

@param1 text,
@param2 text
Select * from tablle1 where field1 like @param1 and (field2 like @param2 OR field2 IS NULL)

My problem is that if I now try to run the SP with a value for @param2 and '%' for @param1 i get all the rows from the table

How can i make this in every situation ? I intend to use this SP in a search form on a asp.net site, and give the users the option to use '%' in searches.(eventually there would me more fields to search for and each one will have a textbox on the page that defaults to '%')

Answer 1

try this

@param1 text,
@param2 text
Select * from tablle1 where field1 like @param1 and isnull(field2,@param2) like @param2 
or
Select * from tablle1 where field1 like @param1 and isnull(field2,'') like @param2 

Answer 2

you should take a look at Sommarskogs homepage

It is the best reference on the subject, and it will also solve some of the other problems you most probably are having with this code.