在PDO中创建多个数据库连接

Question

if I have an array of server ip addresses:

 $servers = array('1.2.3.4','4.5.6.7','7.8.9.10');

how can i loop through them and connect to db, get data from each server, then close?

 foreach ($servers as $v){
    $bdb = new PDO('mysql:host='.$v.';dbname=someDB','user','pass');
    $sel = "SELECT data from table";
    $stmt = $bdb->query($sel);
    while($r = $stmt->fetch()){
          $result[$v]['data'] = $r['data'];
    }
 }

My desired result would be:

    print_r($result);

 array
 (
     [1.2.3.4] => Array
                 (
                   [data] => 'someData'
                 )
     [2.3.4.5] => Array
                 (
                   [data] => 'someOtherData'
                 )
     [7.8.9.10] => Array
                 (
                   [data] => 'someOtherOtherData'
                 )
  )

currently the above code only produces results from the first value in servers array.

I have tried setting $bdb=NULL and unset($bdb) with no luck

Answer 1

I think you have to close the connection after every iteration. Otherwise you have to build an array with connections and don't same them everytime in the same variable.

foreach ($servers as $v){
    $bdb = new PDO('mysql:host='.$v.';dbname=someDB','user','pass');
    $sel = "SELECT data from table";
    $stmt = $bdb->query($sel);
    while($r = $stmt->fetch()){
          $result[$v]['data'] = $r['data'];
    }
    $bdb = null;
}

It should work if you close the connection in that way set your variable to null and delete the connection. Then it should be possible to make a new one in the next iteration.