Oracle Cursor

In Oracle, a cursor is a SELECT statement used to retrieve data row by row from a table or tables.

Syntax

DECLARE
    cursor_name CURSOR FOR
    SELECT column1, column2, ... columnN FROM table_name WHERE condition;
BEGIN
    -- loop to fetch cursor data
END;

In the above syntax:

• cursor_name is the identifier name of the cursor
• column1, column2, ..., columnN are the columns to be retrieved from the table
• table_name is the name of the table from which data will be fetched
• condition is the condition to be applied to filter the data

Example

DECLARE
    cursor_name CURSOR FOR
        SELECT emp_name, salary FROM employees WHERE department = 'Finance';
    emp_name employees.emp_name%TYPE;
    salary employees.salary%TYPE;
BEGIN
    OPEN cursor_name;
    LOOP
        FETCH cursor_name INTO emp_name, salary;
        EXIT WHEN cursor_name%NOTFOUND;
        DBMS_OUTPUT.PUT_LINE('Employee: ' || emp_name || ', Salary: ' || salary);
    END LOOP;
    CLOSE cursor_name;
END;

In the above example, a cursor named cursor_name is declared and opened to retrieve employee names and salaries for those belonging to the Finance department. A loop is used to fetch the data row by row and print it using DBMS_OUTPUT.PUT_LINE.

Conclusion

Oracle cursors are useful for fetching data from tables row by row and processing it in a programmatic manner. They provide a convenient way to process large datasets and perform complex data manipulations.