mysql - 数据库列是否未签名？

Question

使用 Perl DBI，如何检查数据库表的给定列是否未签名？

以下代码无法按预期工作(使用 MySQL 数据库):

my $sth = $dbh->column_info(undef, $schema, $Table, undef);
while (my $Column = $sth && $sth->fetchrow_hashref) {
  my $ColumnName = $Column->{COLUMN_NAME};
  my $data_type = $Column->{DATA_TYPE}; # SQL_DATA_TYPE does not work too
  my $type_info = $dbh->type_info($data_type);
  my $Unsigned = $type_info->{UNSIGNED_ATTRIBUTE};
  my $UnsignedInfo = defined($Unsigned) ? ", unsigned=>$Unsigned" : "";
  print $fh "  '$ColumnName' => {type=>'$Column->{TYPE_NAME}', nullable=>$Column->{NULLABLE}$UnsignedInfo},\n";
}

Answer 1

如果该界面中没有任何原生内容，希望您可以使用 DBI 完成此操作:

create table myTable
(   id int auto_increment primary key,
    si int not null,    -- signed
    ui int unsigned not null    -- unsigned
);

insert myTable (si,ui) values (1,1),(-7,8);

SELECT data_type,column_type  
FROM INFORMATION_SCHEMA.COLUMNS  
WHERE table_schema='so_gibberish' -- my database name
and table_name = 'myTable' AND COLUMN_NAME in ('si','ui');

+-----------+------------------+
| data_type | column_type      |
+-----------+------------------+
| int       | int(11)          |
| int       | int(10) unsigned |
+-----------+------------------+