多组db query轮查，给出统一结果

multi_db_query.php

<?php
$db_conf = array(
    array(
        'host' => '1',
        'port' => '',
        'db' => '1',
        'user' => '1',
        'pwd' => '1',
    ),  
    array(
        'host' => '2',
        'port' => '',
        'db' => '2',
        'user' => '2',
        'pwd' => '2',
    ),  
    ...
    ...
);

function exec_query($query, $count=10){
    global $db_conf;
    $result = array();
    $query = preg_replace('/;$/', '', $query); //如果输入的query后有分号，删掉
    $query = $query.' LIMIT '.$count.';';
    foreach($db_conf as $db){
        $mysqli = new mysqli($db['host'], $db['user'], $db['pwd'], $db['db']);  
        if ($mysqli->connect_errno) {
            printf("Connect failed %s: %s\n", $db['host'], $mysqli->connect_error);
            exit();
        }
        $mysqli->set_charset("utf8");
        $tmp_result =  $mysqli->query($query);
        while ($row = $tmp_result->fetch_assoc()) {
            $result[] = $row;
        }
        $mysqli->close();
    }   
    return $result;
}


if(count($argv)>1 && $argv[1]!= 'command'){
    $limit = isset($argv[2]) ? $argv[2] : 15;
    $rs = ( exec_query($argv[1], $limit));
    if(empty($rs)){
        echo "no results\n";
        die;
    }
    $keys = array_keys($rs[0]);
    foreach($keys as $key){
        echo "$key\t";
    }
    echo "\n";
    foreach($rs as $r){
        foreach($keys as $key){
            echo "$r[$key]\t";
        }
        echo "\n";
    }
}