SQLPlus Define

A value can be assigned to a variable using the command DEF [INE] of SQL * PLUS.
Value defined to be used in a SELECT construction or a file of commands, the variable name prefixind with &. Variables can be emptied using UNDEF [INE].

DEFINE Command Syntax:

DEF[INE] [variable]|[variable = text]

DEFINE Command Examples:

DEFINE product_id
DEFINE product_id = 1521