The SET DEFINE command changes the prefix character used to mark substitution variables. You can use SET DEFINE to turn variable substitution off.
SET DEF[INE] {OFF | ON | prefix_char}
Define is a SQL*Plus client variable. It is NOT a database level setting.
When you start SQL*Plus, variable substitution will be on by default, and the default prefix character is an ampersand. If you are running a script that uses ampersands in text strings, you may want to change the prefix character to something else. If your script doesn’t use substitution variables, you may find it easiest to turn the feature off.
