Query Form Logic: "Like" vs. "Equals"

Question

Our application provides multiple query interfaces that are basically just text inputs. Is there a best practice on whether the backend logic should be pad the query parameter with wildcards then perform a like or should it just do an equals. Of course another option would be to allow user's to use wildcards and then check and use a "like" if appropriate.

I understand the performance implication of using a wildcard like this and that this could be viewed as a subject question, I just want to know if there is a standard practice.

Answer 1

This is something I would leave up to the user, allowing then to actually make a choice. All the UIs I've seen for allowing user-specified conditions have:

• the column to check.
• a drop-down box containing the relationship, such as equal to, not equal to, less than, greater than, starts with.
• the value you want to compare to.

Then, for the starts with option, you just tack on % and use like.

You'll note (for performance reasons which you seem to already understand) I used starts with rather than like to limit the possibility of dragging down the database performance.

I'm not a big fan of unrestricted like statements although you could also provide ends with for those DBMS' capable of storing reversed indexes.