The DECLARE Section
The DECLARE section of a block of PL/SQL code consists of variables, constants, cursor definitions, and special data types. As a PL/SQL programmer, you can declare all types of variables within your blocks of code. However, you must assign a data type to every variable that you define and that data type must conform to Oracle's data type rules. Variables must also conform to Oracle's object naming standards.
Variables are values that are subject to change within a PL/SQL block. PL/SQL variables must be assigned a valid data type upon declaration and can be initialized if necessary. The following example defines a set of variables in the DECLARE portion of a block:
DECLARE owner char(10); tablename char(30); ...