复选框mysql条件混淆:(

Question

我正在尝试使用复选框进行搜索筛选，但是mysql OR和AND条件非常混乱，我如何设置它以显示用户检查的所有结果？我的代码。

<?php 
error_reporting(E_ALL); 
ini_set('display_errors', 1); 

$DB_HOST = "localhost"; 
$DB_NAME = "mysite"; 
$DB_USER = "root"; 
$DB_PASS = "***"; // password edited out 

$conn = new mysqli($DB_HOST, $DB_USER, $DB_PASS, $DB_NAME); 
if($conn->connect_errno > 0) { 
    die('Connection failed [' . $conn->connect_error . ']'); 
} 




$sql="SELECT * FROM websiteusers "; 
if (isset($_POST['submit'])) { 
    $searchgender = isset($_POST['gender']) ? mysqli_real_escape_string($conn,$_POST['gender']) : ''; 

    $searchethnicity = isset($_POST['ethnicity']) ? mysqli_real_escape_string($conn,$_POST['ethnicity']) : ''; 

    $sql .= "WHERE gender = '{$searchgender}'"; 
    $sql .= " OR ethnicity = '{$searchethnicity}' "; 
} 

$query=mysqli_query($conn,$sql) or die(mysqli_error($conn)); 


?> 

<?php 
$query=mysqli_query($conn,$sql) or die(mysqli_error($conn)); 
?> 

<form name="form" action="" method="post"> 
<table> 
    <tr> 
     <td> 
      Gender: 
     </td> 
     <td> 
      <input type="checkbox" name="gender" value="male">Male<br> 
      <input type="checkbox" name="gender" value="female">Female 
     </td> 
    </tr> 
    //more code (it says too much code lol) 

Answer 1

你可以这样做

$sql .= "WHERE gender = '{$searchgender}'"; 

    // if Gender checkbox check then add or ohter wise normal condition 
    if(!empty($searchgender)){ 

    $sql .= " OR "; 
    } 
    $sql .= " ethnicity = '{$searchethnicity}' "; 

Answer 2

//try this 
$sql="SELECT * FROM websiteusers where 1 AND "; 
$searchgender = trim($_POST['gender']); 
$searchethnicity = trim($_POST['searchethnicity']); 
if($searchgender!='') 
{ 
$sql .= " gender = '".$searchgender."'"; 
} 
if($searchgender!='' && $searchethnicity!='') 
$sql .=" OR "; 

if($searchethnicity!='') 
$sql .= " ethnicity = '".searchethnicity."'";