mysql - DBD::mysql - 删除数据库时出现问题

Question

为什么行“$rc = $dbh->func( 'dropdb', $dbname, 'admin' );”删除数据库 db_test_2？

#!/usr/bin/perl
use warnings;
use strict;
use 5.010;
use DBI;

my $host = 'localhost';
my $user = 'user';
my $password = 'password';
my( $rc, $dbname, @databases );



my $drh = DBI->install_driver( 'mysql' );
$dbname = 'db_test_1';

# use a driver handle (drh)

$rc = $drh->func( 'createdb', $dbname, $host, $user, $password, 'admin' );
say for DBI->data_sources( $driver, { host => $host, user => $user, password => $password });
# DBI:mysql:information_schema
# DBI:mysql:db_test_1
# DBI:mysql:mysql


$rc = $drh->func( 'dropdb', $dbname, $host, $user, $password, 'admin' );
say for DBI->data_sources( $driver, { host => $host, user => $user, password => $password });
# DBI:mysql:information_schema
# DBI:mysql:mysql



my $dbh = DBI->connect( "DBI:mysql:", $user, $password, { RaiseError=>1, AutoCommit=>1 } );
$dbname = 'db_test_2';

# reuse the existing connection of a database handle (dbh)

$rc = $dbh->func( 'createdb', $dbname, 'admin' );
say for DBI->data_sources( $driver, { host => $host, user => $user, password => $password });
# DBI:mysql:information_schema
# DBI:mysql:db_test_2
# DBI:mysql:mysql

$rc = $dbh->func( 'dropdb', $dbname, 'admin' );
say for DBI->data_sources( $driver, { host => $host, user => $user, password => $password });
# DBI:mysql:information_schema
# DBI:mysql:db_test_2
# DBI:mysql:mysql

Answer 1

有趣的是，在 DBI func() 中它的定义不同，但是 DBD::MySQL 有一个令人信服的方法来证明什么是真正的 _admin_internal 方法，它是在 Mysql.xs 中定义的，看起来有很多对 do_error() 的调用，这让我相信您应该检查错误。尝试使用 RaiseError => 1 连接并查看其内容。

为此，请连接

  $dbh = DBI->connect("DBI:mysql:database=$db;host=$host",
                      $user, $password, {RaiseError => 1});

然后使用 $dbh->func('dropdb' ...)，看看会发生什么。