如何重读perl数据库查询结果

Question

我想两次使用查询的结果.
如何重新定位指针以便从第二次开始读取结果？
以下示例(为简单起见,只需打印到屏幕):

if ( $dbh = DBI->connect( "DBI:mysql:database=tng;host=ip", "username", "password" ) ) {
    $strSQL = "select * from table";
    if ( $strQuery = $dbh->prepare($strSQL) ) {
        if ( $strQuery->execute() ) {
            while ( @data = $strQuery->fetchrow_array() ) {
                print $data[0];
            }
            --reposition to top and reread the query result and do something else with the data-- $strQuery->finish;
        }
        else {
            $strMsg = "$strDateTime ERROR -- unable to execute statement: " . $strQuery->errstr . "\n";
            print logFile "$strMsg";
        }
    }
    else {
        $strMsg = "$strDateTime ERROR -- unable to prepare statement: " . $dbh->errstr . "\n";
        print logFile "$strMsg";
    }
    $dbh->disconnect();
}
else {
    print logFile "$strDateTime ERROR -- unable to connect to iptables database ... " . DBI->errstr . " \n";
}

Answer 1

您不希望IO库将整个文件加载到内存中以逐行读取它,那么为什么您希望它来自数据库库？

此外,这完全没必要.加载完整的结果非常容易.

my $sth = $dbh->prepare($sql);
my $data = $dbh->selectall_arrayref($sth);

for my $row (@$data) {
    my ($col1, $col2, ...) = @$row;
    ...
}

for my $row (@$data) {
    my ($col1, $col2, ...) = @$row;
    ...
}

如果需要DBI,可以将数据加载到DBD :: Sponge中.