Oracle/PLSQL: Declare a Cursor

A cursor is a SELECT statement that is defined within the declaration section of your PLSQL code. We'll take a look at three different syntaxes for cursors.

Cursor without parameters (simplest)

The basic syntax for a cursor without parameters is:

CURSOR cursor_name
IS
SELECT_statement;

For example, you could define a cursor called c1 as below.

CURSOR c1
IS
    SELECT course_number
      from courses_tbl
      where course_name = name_in;

The result set of this cursor is all course_numbers whose course_name matches the variable called name_in.

Below is a function that uses this cursor.

CREATE OR REPLACE Function FindCourse
   ( name_in IN varchar2 )
   RETURN number
IS
    cnumber number;

    CURSOR c1
    IS
       SELECT course_number
        from courses_tbl
        where course_name = name_in;

BEGIN

open c1;
fetch c1 into cnumber;

if c1%notfound then
     cnumber := 9999;
end if;

close c1;

RETURN cnumber;

END;

Cursor with parameters

The basic syntax for a cursor with parameters is:

CURSOR cursor_name (parameter_list)
IS
SELECT_statement;

For example, you could define a cursor called c2 as below.

CURSOR c2 (subject_id_in IN varchar2)
IS
    SELECT course_number
      from courses_tbl
      where subject_id = subject_id_in;

The result set of this cursor is all course_numbers whose subject_id matches the subject_id passed to the cursor via the parameter.

Cursor with return clause

The basic syntax for a cursor with a return clause is:

CURSOR cursor_name
RETURN field%ROWTYPE
IS
SELECT_statement;

For example, you could define a cursor called c3 as below.

CURSOR c3
RETURN courses_tbl%ROWTYPE
IS
    SELECT *
      from courses_tbl
      where subject = 'Mathematics';

The result set of this cursor is all columns from the course_tbl where the subject is Mathematics.