使用dbi会在perl中产生一个简单错误

$sqlst = $dbh->prepare(\'SELECT * FROM starter_trot WHERE UserId = 2345\' ) or die \"Couldn\'t prepare statement: \" . $dbh->errstr;
$sqlst->execute($userid) or die \"Couldn\'t execute statement: \" . $sqlst->errstr;
my @data;
print\"hai\";
while (@data = $sqlst->fetchrow_array())
{
print \"**\";
}

$sqlst = $dbh->prepare(\'SELECT * FROM starter_trot WHERE USERID = 2345\' ) or        die \"Couldn\'t prepare statement: \" . $dbh->errstr;
$sqlst->execute($userid) or die \"Couldn\'t execute statement: \" . $sqlst->errstr;