SET sql_mode=ORACLE;
create aggregate function f1(x INT) return INT AS
begin
insert into t1(sal) values (x);
return x;
end|
ERROR HY000: Aggregate specific instruction(FETCH GROUP NEXT ROW) missing from the aggregate function
create function f1(x INT) return INT AS
begin
set x=5;
fetch group next row;
return x+1;
end |
ERROR HY000: Non-aggregate function contains aggregate specific instructions: (FETCH GROUP NEXT ROW)
CREATE TABLE marks(stud_id INT, grade_count INT);
INSERT INTO marks VALUES (1,6), (2,4), (3,7), (4,5), (5,8);
SELECT * FROM marks;
stud_id	grade_count
1	6
2	4
3	7
4	5
5	8
# Using PL/SQL syntax: EXCEPTION WHEN NO_DATA_FOUND
CREATE AGGREGATE FUNCTION IF NOT EXISTS aggregate_count(x INT) RETURN INT AS
count_students INT DEFAULT 0;
BEGIN  
LOOP  
FETCH GROUP NEXT ROW;  
IF x THEN  
count_students:= count_students + 1;
END IF;  
END LOOP;  
EXCEPTION
WHEN NO_DATA_FOUND THEN
RETURN count_students;
END aggregate_count //
SELECT aggregate_count(stud_id) FROM marks;
aggregate_count(stud_id)
5
DROP FUNCTION IF EXISTS aggregate_count;
# Using SQL/PSM systax: CONTINUE HANDLER
CREATE AGGREGATE FUNCTION IF NOT EXISTS aggregate_count(x INT) RETURN INT AS
count_students INT DEFAULT 0;
CONTINUE HANDLER FOR NOT FOUND RETURN count_students;
BEGIN  
LOOP  
FETCH GROUP NEXT ROW;  
IF x THEN  
SET count_students= count_students + 1;
END IF;  
END LOOP;  
END //
SELECT aggregate_count(stud_id) FROM marks;
aggregate_count(stud_id)
5
DROP FUNCTION IF EXISTS aggregate_count;
DROP TABLE marks;