Declare Variables, Constants and Types in Oracle PL/SQL

You declare PL/SQL variables, constants and types in declare block. The syntax is

 <name> [CONSTANT] <datatype> [NOT NULL] [:= | DEFAULT <expr>]

is the name of the variable or constant;

may be scalar, composite datatype, reference or LOB;

is a literal value, another variable or any PL/SQL expression. The result of the expression is used to assign the default value of the variable or constant.

If you are defining a constant, you must provide the value of the constant in the definition.

TABLE, RECORD, NESTED TABLE and VARRAY are composite types.

To define scalar type you can refer to [schema.]object%TYPE or cursor%TYPE.

For record type you can refer to [schema.]object%ROWTYPE.

Examples:

DECLARE

  --Define some scalar variables

  v_year NUMBER(4);

  v_pin VARCHAR2(12);

  v_min_amount NUMBER(20, 2) := 25000;

 

  --Define a record type

  TYPE t_customer IS RECORD (

    id NUMBER(18),

    first_name VARCHAR2(32),

    last_name VARCHAR2(32),

  );

  --Declare a record variable

  v_customer t_customer;

 

  --Declare a composite type to hold a list of records

  TYPE t_customer_list IS TABLE OF t_customer;

 

  --Declare a record variable refering an existing table

  v_employee employee%ROWTYPE;

BEGIN

   v_year := 2010;

   -- More PL/SQL code here.

END;

Declare RECORD variables and types
A specific RECORD TYPE corresponding to a fixed number (and datatype) of underlying table columns can simplify the job of defining variables.
%TYPE is used to declare a field with the same type as that of a specified table’s column.%ROWTYPE is used to declare a record with the same types as found in the specified database table, view or cursor.
Declare RECORD type

TYPE <type_name> IS RECORD(

    <field_declaration>,...);

Each record field is declared with its ‘field_declaration’:

   <field_name> {<field_type> |

               <variable>%TYPE |

               <table.column>%TYPE |

               <table>%ROWTYPE}

               [ [NOT NULL] {:= | DEFAULT} <expr> ]

The can be any PL/SQL data type except REF CURSOR.
To declare a record variable:

   <variable_identifier> <type_name>;

You can declare a variable based on a record reference using %ROWTYPE:

   <variable_name> <table_or_curosr_name>%ROWTYPE

The number of variables and their data type is evaluated at run-time.

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Declare Variables, Constants and Types in Oracle PL/SQL

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