sql tables

For the past couple of days I've been working on sql injections, and today I found another vulnerable site. When I put an ' into the url (.php?id=') I got an error that said the following:

MYSQL ERROR —————————————————–– You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''''' at line 2

  query - SELECT categories_id, categories_name, parent_id FROM shop_categories  
                            WHERE categories_id = '''

So my question is, is shop_categories the name of a table that contains the columns named, categories_id, categories_name, and parent_id ?

thanks for any help.

http://www.w3schools.com/sql/sql_select.asp

SELECT fieldlist FROM table WHERE field = *

http://www.unixwiz.net/techtips/sql-injection.html

Thanks for the quick responses.:)