php - 检查是否存在于数据库 mysqli_num_rows

Question

$check = mysqli_real_escape_string($link, $_REQUEST['email']);
$sql = "SELECT * FROM users WHERE email = '$check'";
if (mysqli_num_rows($sql) == 0)
{
 echo "1";
}
else 
{
echo "0";
}

我正在尝试检查数据库中是否存在电子邮件，但是无论我为 if (mysqli_num_rows($sql) == 0 添加什么值，我都只返回结果 1 或0 如果电子邮件存在或不存在。一些想法？

Answer 1

您没有使用 mysqli_query 运行 sql 语句

必须先查询sql语句再统计行数

$conn = mysqli_connect("127.0.0.1", "my_user", "my_password", "my_db");
/*mysqli connection*/

$check = mysqli_real_escape_string($link, $_REQUEST['email']);
    $sql = "SELECT * FROM users WHERE email = '$check'";
    $res = mysqli_query($conn,$sql);
      if (mysqli_num_rows($res ) == 0){
    }