如何在mysqli中使用php变量？

Question

这有效

<?php

         $result = $conn->query('SELECT * FROM people
         WHERE user="55"') or die(mysql_error());  

        $row = mysqli_fetch_array( $result );
         echo $row['name'];
?>

但是当我尝试使用php变量时，以下内容不起作用：

<?php

     $a = 55; 
     $result = $conn->query('SELECT * FROM people
     WHERE user="$a"') or die(mysql_error());  

    $row = mysqli_fetch_array( $result );
     echo $row['name'];
?>

Answer 1

试试这个：

$query = 'SELECT * FROM people  WHERE user="'.$a.'"';

Answer 2

您必须连接如下所示的值

<?php $result = $conn->query('SELECT * FROM people  WHERE user="'.$a.'"') or die(mysql_error());  

    $row = mysqli_fetch_array( $result );
     echo $row['name']; ?>

Answer 3

更改此内容： $ result = $ conn-＆gt; query（＆＃39; SELECT * FROM people WHERE user =＆＃34; $ a＆＃34;＆＃39;）或die（mysql_error（））;

至此： $ result = $ conn-＆gt; query（＆＃34; SELECT * FROM people WHERE user =＆＃39; $ a＆＃39;＆＃34;）或die（mysql_error（））;