Defining records, PL-SQL Programming

Defining and Declaring Records

To create records, you have to define a RECORD type, and then declare records of that type. You may also define RECORD types in the declarative part of any PL/SQL subprogram, block,  or package using the syntax as shown:

TYPE type_name IS RECORD (field_declaration[,field_declaration]...);

where field_declaration stands for

field_name field_type [[NOT NULL] {:= | DEFAULT} expression]

And where the type_name is a type specifier used later to declare the records, field_ type is any PL/SQL datatype except REF CURSOR, and expression yields a value of the similar type as the field_type.

Note:  Unlike the TABLE and VARRAY types, the RECORD types cannot be CREATED and stored in the database.

You can use %TYPE & %ROWTYPE to state the field types. In the illustration shown below, you define a RECORD type named DeptRec:

DECLARE

TYPE DeptRec IS RECORD (

dept_id dept.deptno%TYPE,

dept_name VARCHAR2(15),

dept_loc VARCHAR2(15));

Notice that the field declarations are just like the variable declarations. Each field has an exclusive name and specific datatype. Therefore, the value of a record is actually a collection of values, each of some of the simpler type.

As the illustration below shows, the PL/SQL defines records that contain collections, objects, and other records (known as the nested records). Though, the object types cannot have attributes of type RECORD.

DECLARE

TYPE TimeRec IS RECORD (

seconds SMALLINT,

minutes SMALLINT,

hours SMALLINT);

TYPE FlightRec IS RECORD (

flight_no INTEGER,

plane_id VARCHAR2(10),

captain Employee, -- declare object

passengers PassengerList, -- declare varray

depart_time TimeRec, -- declare nested record

airport_code VARCHAR2(10));

The illustration later shows that you can specify a RECORD type in the RETURN clause of a function specification. That permits the function to return a user-defined record of the same type.

DECLARE

TYPE EmpRec IS RECORD (

emp_id INTEGER

last_name VARCHAR2(15),

dept_num INTEGER(2),

job_title VARCHAR2(15),

salary REAL(7,2));

...

FUNCTION nth_highest_salary (n INTEGER) RETURN EmpRec IS...

Posted Date: 10/4/2012 3:35:49 AM | Location : United States







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