Question

请帮我优化以下foreach循环。它适用于小型数组，当循环很短但问题是，有时，当数组变大时，它会强制查询在foreach内循环很多次，这导致我的服务器阻塞抛出一个503错误。我需要以某种方式在foreach之外进行查询，但仍然能够选择WHERE cat = $ id [0] AND sub = $ id [1] AND fir = $ id [2]。

foreach($array as $id){
    $query=mysqli_query($con,"SELECT * FROM table WHERE cat=$id[0] AND sub = $id[1] AND fir = $id[2]");

    $thiss = mysqli_fetch_array($query);
    echo $thiss['name']; 
}

Answer 1

$ands = array();
foreach ($array as $id) {
    $ands[] = "(cat=$id[0] AND sub = $id[1] AND fir = $id[2])";
}
$ors = implode(' OR ', $ands);
$query = mysqli_query($con, "SELECT name FROM TABLE WHERE $ors";
while ($thiss = mysqli_fetch_assoc($query)) {
    echo $thiss['name'];
}

Answer 2

我不会详细说明为什么我建议你重新考虑你的查询逻辑，但对于手头的任务，试试这个：

$where=array();
foreach($array as $id){
  $where[]="cat=$id[0] AND sub = $id[1] AND fir = $id[2]";
}
$sql='SELECT * FROM table WHERE ('.implode(') OR (',$where).')';
$query=mysqli_query($con,$sql);
while ($thiss = mysqli_fetch_array($query))
  echo $thiss['name'];

Answer 3

试试这个

$cat = $sub = $fir = '';
foreach($array as $id){
  $cat .= $id[0].',';
  $sub .= $id[1].',';
  $fir .= $id[2].',';
}
$cat = substr_replace($cat, '', -1);
$sub = substr_replace($sub, '', -1);
$fir = substr_replace($fir, '', -1);
$sql = "SELECT * FROM table WHERE `cat` IN ($cat) AND `sub` IN($sub) AND `fir` IN ($fir)";
$query=mysqli_query($con,$sql);
while ($row = mysqli_fetch_array($query)) {
   echo $row['name']; 
}

在PHP foreach循环中优化MySql Select查询

3 个答案: