Range-type window frame supports only numeric datatype

create table t1 (a int, b varchar(5));

insert into t1 values (1,'a'), (2, 'b'), (3, 'c');

select sum(a) over (order by b range between unbounded preceding and current row) from t1;

MariaDB [test]> select sum(a) over (order by b range between unbounded preceding and current row) from t1;

ERROR 4021 (HY000): Numeric datatype is required for RANGE-type frame

mysql> select sum(a) over (order by b range between unbounded preceding and current row) from t1;

+----------------------------------------------------------------------------+

| sum(a) over (order by b range between unbounded preceding and current row) |

+----------------------------------------------------------------------------+

|                                                                          1 |

|                                                                          3 |

|                                                                          6 |

+----------------------------------------------------------------------------+

3 rows in set (0.00 sec)

MariaDB [test]> select sum(a) over (range between unbounded preceding and current row) from t1;

ERROR 4019 (HY000): RANGE-type frame requires ORDER BY clause with single sort key

mysql> select sum(a) over (range between unbounded preceding and current row) from t1;

+-----------------------------------------------------------------+

| sum(a) over (range between unbounded preceding and current row) |

+-----------------------------------------------------------------+

|                                                               6 |

|                                                               6 |

|                                                               6 |

+-----------------------------------------------------------------+

3 rows in set (0.00 sec)