问错误过程MYSQL

EN

  CREATE PROCEDURE add_Drug(IN animal INTEGER)
  BEGIN
    DECLARE Code VARCHAR(30);
    DECLARE i, eof INT DEFAULT 0;

    DECLARE cdrugs CURSOR FOR 
      SELECT P.Code_drug 
        FROM   Prescription P
        WHERE  P.Id_animal = animal
          AND (P.End_date IS NULL OR P.End_date >= CURDATE());

    DECLARE CONTINUE HANDLER FOR NOT FOUND SET eof = 1;

    # the function counter returns the greater id of the table PhysicalDrug incremented by one
    SET @Id = counter();
    OPEN cdrugs;
    read_loop: LOOP
      FETCH cdrugs INTO Code;
      IF eof = 1 THEN
        LEAVE read_loop;
      END IF;
      #Memorize the number of units of the drug present in the clinic 
      SET @NumberDrug =
        (SELECT COUNT(*) 
          FROM PhysicalDrug
          WHERE Code_drug = Code);
      IF @NumberDrug < 5 THEN
        WHILE i < 10 DO
          INSERT INTO PhysicalDrug (Id, Code_drug)
            VALUES (@Id, Code);
          SET i = i + 1;
          SET @Id = @Id + 1;
        END WHILE;
      END IF;
    END LOOP;
    CLOSE cdrug;
  END //
  DELIMITER ;