Centos 7

Sorry, can you clarify please?
In the above script you have a REVERSE loop and direct bound order. It performs no iterations and produces no output.
This looks correct.

I just checked all four combinations and I think they give correct results:

Direct loop, direct bound order (3 iterations as expected)

SET SQL_MODE=ORACLE;

delimiter //

#

DECLARE

  totalprice DECIMAL(12,2):=NULL;

  loop_start INTEGER := 1;

BEGIN

  FOR idx IN loop_start..3 LOOP

    SELECT idx;

  END LOOP;

END;

//

delimiter ;

+-----+

| idx |

+-----+

|   1 |

+-----+

1 row in set (0.01 sec)

+-----+

| idx |

+-----+

|   2 |

+-----+

1 row in set (0.01 sec)

+-----+

| idx |

+-----+

|   3 |

+-----+

1 row in set (0.01 sec)

Query OK, 0 rows affected (0.00 sec)

Direct loop, reverse bound order (no iterations as expected)

SET SQL_MODE=ORACLE;

delimiter //

#

DECLARE

  totalprice DECIMAL(12,2):=NULL;

  loop_start INTEGER := 1;

BEGIN

  FOR idx IN 3..loop_start LOOP

    SELECT idx;

  END LOOP;

END;

//

delimiter ;

Query OK, 0 rows affected (0.00 sec)

Reverse loop, reverse bound order (3 iterations as expected)

SET SQL_MODE=ORACLE;

delimiter //

#

DECLARE

  totalprice DECIMAL(12,2):=NULL;

  loop_start INTEGER := 1;

BEGIN

  FOR idx IN REVERSE 3..loop_start LOOP

    SELECT idx;

  END LOOP;

END;

//

delimiter ;

+-----+

| idx |

+-----+

|   3 |

+-----+

1 row in set (0.00 sec)

+-----+

| idx |

+-----+

|   2 |

+-----+

1 row in set (0.00 sec)

+-----+

| idx |

+-----+

|   1 |

+-----+

1 row in set (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

Reverse loop, direct bound order (no iterations as expected)

SET SQL_MODE=ORACLE;

delimiter //

#

DECLARE

  totalprice DECIMAL(12,2):=NULL;

  loop_start INTEGER := 1;

BEGIN

  FOR idx IN REVERSE loop_start..3 LOOP

    SELECT idx;

  END LOOP;

END;

//

delimiter ;

Query OK, 0 rows affected (0.00 sec)

The following is from the oracle documentation. If I am reading it correctly, your example 3 above should not produce results, while example 4 should.

Thx

https://docs.oracle.com/database/121/LNPLS/for_loop_statement.htm#LNPLS1515

[ REVERSE ] lower_bound .. upper_bound

lower_bound and upper_bound must evaluate to numbers (see "Lower Bound and Upper Bound"). PL/SQL evaluates lower_bound and upper_bound once, when the FOR LOOP statement is entered, and stores them as temporary PLS_INTEGER values, rounding them to the nearest integer if necessary.

If lower_bound equals upper_bound, the statements run only once.

If lower_bound does not equal upper_bound when the FOR LOOP statement begins to run, then:

If REVERSE is omitted:

If lower_bound is greater than upper_bound, the statements do not run, and control transfers to the statement after the FOR LOOP statement.

Otherwise, lower_bound is assigned to index, the statements run, and control returns to the top of the loop, where index is compared to upper_bound. If index is less than upper_bound, index is incremented by one, the statements run again, and control returns to the top of the loop. When index is greater than upper_bound, control transfers to the statement after the FOR LOOP statement.

If REVERSE is specified:

If upper_bound is less than lower_bound, the statements do not run, and control transfers to the statement after the FOR LOOP statement.

Otherwise, upper_bound is assigned to index, the statements run, and control returns to the top of the loop, where index is compared to lower_bound. If index is greater than lower_bound, index is decremented by one, the statements run again, and control returns to the top of the loop. When index is less than lower_bound, control transfers to the statement after the FOR LOOP statement.

Right, Oracle returns the following output:

SET SERVEROUTPUT ON;

DROP PROCEDURE p1;

CREATE PROCEDURE p1 AS

  loop_start INTEGER := 1;

BEGIN

  FOR idx IN REVERSE 3..loop_start LOOP

    DBMS_OUTPUT.PUT_LINE('idx='||idx);

  END LOOP;

END;

/

CALL p1();

Call completed.

SET SERVEROUTPUT ON;

DROP PROCEDURE p1;

CREATE PROCEDURE p1 AS

  loop_start INTEGER := 1;

BEGIN

  FOR idx IN REVERSE loop_start..3 LOOP

    DBMS_OUTPUT.PUT_LINE('idx='||idx);

  END LOOP;

END;

/

CALL p1();

idx=3

idx=2

idx=1

Call completed.

Sorry, I overlooked this.

Will fix MariaDB accordingly. Thanks for clarification.

Forgot to close. Was fixed in 10.3.11 on Nov 13.