Cursor Variables

Declaring and Opening Cursor Variables

Memory is usually allocated for a cursor variable in the client application using the appropriate ALLOCATE statement. In Pro*C, use the EXEC SQL ALLOCATE <cursor_name> statement. In OCI, use the Cursor Data Area.

You can also use cursor variables in applications that run entirely in a single server session. You can declare cursor variables in PL/SQL subprograms, open them, and use them as parameters for other PL/SQL subprograms.

Examples of Cursor Variables

This section includes several examples of cursor variable usage in PL/SQL. For additional cursor variable examples that use the programmatic interfaces, see the following manuals:

Fetching Data

The following package defines a PL/SQL cursor variable type Emp_val_cv_type, and two procedures. The first procedure, Open_emp_cv, opens the cursor variable using a bind variable in the WHERE clause. The second procedure, Fetch_emp_ data, fetches rows from the Emp_tab table using the cursor variable.

CREATE OR REPLACE PACKAGE Emp_data AS

TYPE Emp_val_cv_type IS REF CURSOR RETURN Emp_tab%ROWTYPE;

Using Procedures and Packages 7-31

Cursor Variables

The following example shows how to call the Emp_data package procedures from a PL/SQL block:

DECLARE

--declare a cursor variable Emp_curs Emp_data.Emp_val_cv_type; Dept_number Dept_tab.Deptno%TYPE; Emp_row Emp_tab%ROWTYPE;

BEGIN

Dept_number := 20;

--open the cursor using a variable Emp_data.Open_emp_cv(Emp_curs, Dept_number);

--fetch the data and display it LOOP

Emp_data.Fetch_emp_data(Emp_curs, Emp_row); EXIT WHEN Emp_curs%NOTFOUND; DBMS_OUTPUT.PUT(Emp_row.Ename || ' '); DBMS_OUTPUT.PUT_LINE(Emp_row.Sal);

END LOOP;

END;

Implementing Variant Records

The power of cursor variables comes from their ability to point to different cursors. In the following package example, a discriminant is used to open a cursor variable to point to one of two different cursors:

BEGIN

IF Discrim = 1 THEN

OPEN Cv FOR SELECT * FROM Emp_tab WHERE Sal > 2000;

7-32 Oracle Database Application Developer's Guide - Fundamentals