SQL checking if a value is an empty string?

Question

This is the where clause of my query:

WHERE person.personstatusuid = @StatusUID
           AND person.forename != ''

this works fine - @StatusUID is coming from a drop down box.

However, I also have a location field. This code works fine too:

WHERE person.personstatusuid = @StatusUID AND person.forename != '' AND person.Location = @Location

I want to change the last line to be if it is the @Location (which comes from a text box) or the @Location is empty.

I tried using an OR as was suggested, but no matter what I try, it does not return any rows. I have tried replacing the line with this, just for testing purposes:

   AND (@Location NOT LIKE 'BISCUITS' )

   AND (@Location!='' )

   AND (LEN(@Location) == 0 )

but none of them work when I leave the text box blank.

Any ideas?

Answer 1

Try this

WHERE   person.personstatusuid = @StatusUID 
AND  person.forename != '' 
AND  (ISNULL(@Location,'') = '' OR person.Location = @Location)