[Koha] Learning SQL

Could anyone suggest a good resource (online, print, or in-person) for learning SQL? We would like to have a better understanding so we can more easily create and modify reports. Thank you, Eva Radding Librarian Facing History and Ourselves 16 Hurd Road Brookline, MA 02445 617-735-1680 Eva_Radding@facing.org This email and any information attached to it may be confidential. If you are not the intended recipient, any use or dissemination of the information is prohibited. Please notify the sender that you received the email in error and delete any record of this message.