Data Type In PL/SQL

Every Variable has data type. Oracle provides many predefined data types or sub type.

PL/SQL supports four data type:

1. Scalar Data Type
2. Composite Data Type
3. Reference Data Type
4. LOB Data Type

1. Scalar Data Type:
It holds a single value and it supports Boolean type.

Scalar Data Types are classified into four categories :

Data Type	Description
Numeric	Numeric data type is used for arithmetic operations like PLS_INTEGER, BINARY_INTEGER,NUMBER etc.
Character	Alphanumeric value which represent single character or strings of characters or sub type like CHAR,VARCHAR2,NCHAR,NVARCHAR2 etc
Boolean	Boolean data type are used for logical operations like TRUE and FALSE.
Datetime	Date data type is used for store the date and time.

Example Of Sub type:

DECLARE
   SUBTYPE NAME IS char(20);
   SUBTYPE MSG IS varchar2(100);
   USER_NAME NAME;
   WEL_MSG MSG;
BEGIN
   USER_NAME := 'Reader ';
   WEL_MSG := 'Welcome to the World of PL/SQL';
   dbms_output.put_line('Hello ' || USER_NAME||' '|| WEL_MSG);
END;

2. Composite Data Type:
In Composite datatype we can store whole row, if one row have three columns so we can store three values in a composite datatype variable at a time. 

Type Of Composite Data Type :

• RECORDS 
• COLLECTIONS

3. Reference Data Type:
It holds values , acting as pointers which pointers to other data items like REF CURSOR.


4. LOB Data Type:
LOB data type hold values called Locators, which specifying the location of large objects like graphic images, video clips, and sound wave forms.