PHP and MySQL optional WHERE conditions

Question

I have the following problem: I want to let a user apply filters to a DB search. I have three filters, A, B and C. All of them can be \"empty\", as in, the user doesn\'t care a

Answer 1

Try doing something like this:

if @param1 is not null
   select * from table1 where col1 = @param1
else
   select * from table1 where col2 = @param2

This can be rewritten:

select * from table1
where (@param1 is null or col1 = @param1)
  and (@param2 is null or col2 = @param2)

Got the idea from Baron Schwartz's blog: https://www.xaprb.com/blog/2005/12/11/optional-parameters-in-the-where-clause/