Equals(=) vs. LIKE

Question

When using SQL, are there any benefits of using = in a WHERE clause instead of LIKE?

Without any special operators, LIKE

Answer 1

If you search for an exact match, you can use both, = and LIKE.

Using "=" is a tiny bit faster in this case (searching for an exact match) - you can check this yourself by having the same query twice in SQL Server Management Studio, once using "=", once using "LIKE", and then using the "Query" / "Include actual execution plan".

Execute the two queries and you should see your results twice, plus the two actual execution plans. In my case, they were split 50% vs. 50%, but the "=" execution plan has a smaller "estimated subtree cost" (displayed when you hover over the left-most "SELECT" box) - but again, it's really not a huge difference.

But when you start searching with wildcards in your LIKE expression, search performance will dimish. Search "LIKE Mill%" can still be quite fast - SQL Server can use an index on that column, if there is one. Searching "LIKE %expression%" is horribly slow, since the only way SQL Server can satisfy this search is by doing a full table scan. So be careful with your LIKE's !

Marc