Commercial database systems require more user-friendly query languages. We will look at

• SQL in detail.
• QBE briefy in the next chapter.
• Quel briefy in the next chapter.

Although referred to as query languages, they each contain facilities for designing and modifying the database.

1. The relation schemes for the banking example used throughout the new edition of the textbook are:

• Branch-scheme = (bname, bcity, assets)
• Customer-scheme = (cname, street, ccity)
• Depositor-scheme = (cname, account#)
• Account-scheme = (bname, account#, balance)
• Loan-scheme = (bname, loan#, amount)
• Borrower-scheme = (cname, loan#)