MariaDB [test]> drop table if exists i1, i2, i3;

Query OK, 0 rows affected (0.035 sec)

MariaDB [test]> create table i1 (a decimal(38,38));

Query OK, 0 rows affected (0.014 sec)

MariaDB [test]> insert into i1 values (-0.9999999999999999999999999999999999999), (0.9999999999999999999999999999999999999);

Query OK, 2 rows affected (0.004 sec)

Records: 2  Duplicates: 0  Warnings: 0

MariaDB [test]> select format(a,0), format(a,38) from i1;

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

| format(a,0) | format(a,38)                      |

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

| -1          | -1.000000000000000000000000000000 |

| 1           | 1.000000000000000000000000000000  |

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

2 rows in set (0.001 sec)

MariaDB [test]> create table i2 as select format(a,0) from i1;

ERROR 1406 (22001): Data too long for column 'format(a,0)' at row 1

MariaDB [test]> create table i3 as select format(a,38) from i1;

ERROR 1406 (22001): Data too long for column 'format(a,38)' at row 1

MariaDB [test]> delete from i1;

Query OK, 2 rows affected (0.003 sec)

MariaDB [test]> create table i2 as select format(a,0) from i1;

Query OK, 0 rows affected (0.016 sec)

Records: 0  Duplicates: 0  Warnings: 0

MariaDB [test]> show create table i2;

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

| Table | Create Table                                                                                                          |

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

| i2    | CREATE TABLE `i2` (

  `format(a,0)` varchar(1) CHARACTER SET utf8 DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=latin1 |

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

1 row in set (0.000 sec)

MariaDB [test]> create table i3 as select format(a,38) from i1;

Query OK, 0 rows affected (0.017 sec)

Records: 0  Duplicates: 0  Warnings: 0

MariaDB [test]> show create table i3;

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

| Table | Create Table                                                                                                            |

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

| i3    | CREATE TABLE `i3` (

  `format(a,38)` varchar(32) CHARACTER SET utf8 DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=latin1 |

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

1 row in set (0.001 sec)