Cursors

Simple cursors are supported inside stored procedures and functions. The syntax is as in embedded SQL. Cursors are currently asensitive, read-only, and non-scrolling. Asensitive means that the server may or may not make a copy of its result table.

For example: 

CREATE PROCEDURE curdemo()
BEGIN
  DECLARE done INT DEFAULT 0;
  DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = 1;
  DECLARE cur1 CURSOR FOR SELECT id,data FROM test.t1;
  DECLARE cur2 CURSOR FOR SELECT i FROM test.t2;
  DECLARE a CHAR(16);
  DECLARE b,c INT;
  OPEN cur1;
  OPEN cur2;
  REPEAT
    FETCH cur1 INTO a, b;
    FETCH cur2 INTO c;
    IF NOT done THEN
       IF b < c THEN
          INSERT INTO test.t3 VALUES (a,b);
       ELSE
          INSERT INTO test.t3 VALUES (a,c);
       END IF;
    END IF;
  UNTIL done END REPEAT;
  CLOSE cur1;
  CLOSE cur2;
END

Declaring Cursors

DECLARE cursor_name CURSOR FOR sql_statement

Multiple cursors may be defined in a routine, but each must have a unique name.

Cursor OPEN Statement

OPEN cursor_name

This statement opens a previously declared cursor.

Cursor FETCH Statement

FETCH cursor_name

This statement fetches the next row (if a row exists) using the specified open cursor, and advances the cursor pointer.

Cursor CLOSE Statement

CLOSE cursor_name

This statement closes a previously opened cursor.