如何在mysqli中使用php變量？

Question

這工作

<?php 

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

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

但是當我嘗試使用PHP變量，下面不工作：

<?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

試試這個：

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

Answer 2

你必須Concat的像值低於

<?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： $ result = $ conn-> query（'SELECT * FROM people WHERE user =「$ a」'）或die（mysql_error（））;

這樣： $結果= $ conn->查詢（ 「SELECT * FROM人WHERE用戶= '$ A'」）或死亡（mysql_error（））;