Calculate storage of DECIMAL(m,d)

gistfile1.txt

Storage of `DECIMAL(_m_,_d_)` can be calculated with this function:

```sql
DELIMITER $$
CREATE FUNCTION `fn_DECIMAL_SIZE`(`M` INT, `D` INT) RETURNS int(11)
    DETERMINISTIC
BEGIN
set @m = m;
set @d = d;


set @i = @m-@d;

set @size =         4 * floor( @i/9 );
set @size = @size + ceil( (@i % 9) / 2 );

set @size = @size + 4 * floor( @d/9 );
set @size = @size + ceil( (@d % 9) / 2 );

return @size;
END$$
DELIMITER ;
```

[source](https://dev.mysql.com/doc/refman/8.0/en/precision-math-decimal-characteristics.html)

to create a list of some values use:
```sql
select m, d, fn_DECIMAL_SIZE(m,d)
from (
	(select seq as m from seq_1_to_20) _m
    join
	(select seq as d from seq_0_to_6) _d
)
where m>d;
```