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我需要评估用户是否在特定日期之后登录系统。为此，MySQL 数据库中有三个表，用户、调查和登录。调查包含需要与用户上次登录比较的时间点的日期。这是问题。

当我使用“？” 占位符，生成的 num_rows 计数始终为 0。但是当我在将查询语句交给 $mysqli->prepare() 之前分配值时，该过程按预期工作。不知何故， store_result() 没有选择该列。这是我的代码：

 if (isset($userId)){
//get survey release date
$res3 = $mysqli->query("SELECT sur_date,sur_url FROM survey ORDER BY sur_id DESC limit 1");
$array = $res3->fetch_assoc();
$theta_date = $array['sur_date'];
//$theta_date = "2013-01-18 01:00:00";

   //this didn't generate errors, but didn't output the correct result either.
   //$query = "SELECT login_id FROM logins WHERE login_user=? AND login_date>=?";
   //if ($stmt = $mysqli->prepare($query)){
   // $stmt->bind_param('ss',$userID,$theda_date);
   // $stmt->execute();

  //this works
  $query = "SELECT login_id FROM logins WHERE login_user='$userId' AND login_date>='$theta_date'";
    if ($stmt = $mysqli->prepare($query)){
    $stmt->execute() or die("The query did not work");

    //if number is greater than 0 do something
    $stmt->store_result();
      printf("The number of login ids after theta are %d",$stmt->num_rows);
  $stmt->close();
}else{
   echo "The query did not execute.";
}
 }else{
   echo "The User ID was not valid.";
   exit();
 }
 $mysqli->close();

任何见解都会有所帮助，

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1 回答 1

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准备好的语句似乎与 $theta_date 日期时间格式有问题。$theta_date 在调查表中存储为“2013-01-18 01:00:00”。bind_param() 试图解析 $theta_date 作为参考。这是解决方案：

 //convert datetime to Unix timestamp with strtotime()
 $theta_date = $array['sur_date'];
 $timestamp = strtotime($theta_date);

 //In the prepared statement, use MySQL FROM_UNIXTIME function to convert timestamp
 $query = "SELECT login_id FROM logins WHERE login_user=? AND login_date>=FROM_UNIXTIME(?)";

 //changed the parameter types to integer and bound $timestamp to second placeholder
 if ($stmt = $mysqli->prepare($query)){
   $stmt->bind_param('ii',$userId,$timestamp);
   $stmt->execute();

//the rest is the same
 $stmt->store_result();
   printf("The number of login ids after theta are %d",$stmt->num_rows);
   $stmt->close();
}

那是一种痛苦。

于 2013-01-20T00:35:18.490 回答