if( CheckVersion( $DBversion ) ) {
# you can use $dbh here like:
$dbh->do( "ALTER TABLE borrower_modifications ALTER COLUMN changed_fields MEDIUMTEXT DEFAULT NULL" );
$dbh->do( "ALTER TABLE borrower_modifications MODIFY changed_fields MEDIUMTEXT DEFAULT NULL" );
# Always end with this (adjust the bug info)
NewVersion( $DBversion, 25086, "Set changed_fields column of borrower_modifications as nullable");
-