PL/SQL Constants

As the name implies a constant is a value used in a PL/SQL Block that remains unchanged throughout the program. A constant is a user-defined literal value. You can declare a constant and use it instead of actual value.
For example: 

Advantages of PL/SQL

These are the advantages of PL/SQL.

• Block Structures: PL SQL consists of blocks of code, which can be nested within each other. Each block forms a unit of a task or a logical module. PL/SQL Blocks can be stored in the database and reused.

PL/SQL Variables

PL/SQL Placeholders

Placeholders are temporary storage area. Placeholders can be any of Variables, Constants and Records. Oracle defines placeholders to store data temporarily, which are used to manipulate data during the execution of a PL SQL block.

Depending on the kind of data you want to store, you can define placeholders with a name and a datatype. Few of the datatypes used to define placeholders are as given below.
Number (n,m) , Char (n) , Varchar2 (n) , Date , Long , Long raw, Raw, Blob, Clob, Nclob, Bfile

PL/SQL Variables

These are placeholders that store the values that can change through the PL/SQL Block.

The General Syntax to declare a variable is:

What is PL/SQL?

What is PL/SQL?

PL/SQL stands for Procedural Language extension of SQL.

PL/SQL is a combination of SQL along with the procedural features of programming languages. It was developed by Oracle Corporation in the early 90’s to enhance the capabilities of SQL.