There are three constructs in SQL that allow us to update the tables of a
relational database: update, insert, and delete.
The update construct modifies components of tuples. It applies to all tuples
of the specified table unless limited by a where clause.
Example 5.21.1 Recall the table EMPHIST introduced in Example 3.3.5. A
script to create and populate the tables discussed in that example is contained
in the script ced.sql that is available in Appendix C.
To give all current employees a 10% raise, we apply the following update
phrase: