几年后我会回到这里…生活让我走上了一条不同的道路，但我又回到了这一步，仍然试图找到一些有用的东西。
我不是一个专业的前端开发人员，我正在学习，但为了“代码优先，学习第二”的兴趣，我正在尝试使用mysql存储过程提供的多个下拉菜单加载一个页面。虽然我总是对“最好的方法”感兴趣（例如，“你为什么不做面向对象编程？”或者“你为什么要这么做？”，我只想说我在学习，但现在，我只是想弄明白“为什么这不管用？”我在YouTube上看了很多视频——在这里搜了很多文章——但仍然搞不清这是怎么回事。这看起来应该比现在简单得多，而且不明白为什么我不能让它工作，即使这不是最佳实践。我观看的视频不可避免地展示了如何使用（单个）过程填充下拉列表。我可以得到一个（单个）下拉列表来填充；我不能在同一页上得到两个或更多。
我数据库中的表过于简单，再说一遍，并不是真正的重点。我有一个“year”表，基本上（为了简单起见）有一个“id”，它是年份，还有一个列（也是年份）。
所以：

year_id  year
2017     2017
2018     2018

team_seq  team_name
1         joe_smith
2         tom_jefferson

    $qry1 = "Select ... <the rest of the Team query"
    $qry2 = "Select ... <the rest of the Year query"

<form method="post" action="">

<?php
  require_once('../../../mysqlconnect_mysqli.php'); 

  /* TEAM DROPDOWN */

    $qry1 = "CALL ref_sp_Team_Ref()";

    $teams = mysqli_query($conn,$qry1);

    if (mysqli_num_rows($teams) > 0)
    {
      echo "<label for='teams'>Teams: </label>";
      echo "<select name='teams' size='1' required>";   
      echo "<option>Team Names</option>";

      while($row = mysqli_fetch_array($teams))
        {
          echo "<option value=\"{$row['team_seq']}\">{$row['team']}</option>";         
        }

      echo "</select>";
      echo "<br /><br />";

    }
    else
    {
      echo "Why is this empty?";
    }

    mysqli_free_result($teams);


  /* YEAR DROPDOWN */
    $qry2 = "CALL ref_sp_Year_Ref()";

    $years = mysqli_query($conn,$qry2);

    if (mysqli_num_rows($years) > 0)
    {
      echo "<label for='years'>Years: </label>";
      echo "<select name='years' size='1' required>";   
      echo "<option>Seasons</option>"; 

      while($row = mysqli_fetch_array($years))
        {
          echo "<option value=\"{$row['year_id']}\">{$row['year']}</option>";         
        }

      echo "</select>";
      echo "<br /><br />";

    }
    else
    {
      echo "Why is this empty?";
    }    

    mysqli_free_result($years);

  echo " <input type='submit' name='submit1' value='Get Results'/>";
  echo "</form>";

?>

<form method="post" action="">

<p>
Years: 
    <select name="years">
    <?php 
    #the following returns the connection variable $dbh
    require_once('../../../mysqlconnect_mysqli.php');   
    $sql = "call ref_sp_Year_Ref";

    if ($mysqli->multi_query($sql))
    {
       #Get first data set from Procedure - do nothing with it
       $result = $mysqli->store_result();  


       while($row = mysqli_fetch_array($result,MYSQLI_ASSOC))
       {
       echo     
          "<option value='" . $row['year_id'] . "'>" . $row['year'] . "</option>";  
       }
       mysqli_free_result($result);

    }         
    ?>
</select>       
</p>

<p>
Teams: 
    <select name="teams">
    <?php 
    #the following returns the connection variable $dbh
    require_once('../../../mysqlconnect_mysqli.php');       
    $sql = "call ref_sp_Team_Ref";      

    if ($mysqli->multi_query($sql))
    {
       #Get first data set from Procedure - do nothing with it
       $result = $mysqli->store_result();  


       while($row = mysqli_fetch_array($result,MYSQLI_ASSOC))
       {
       echo     
          "<option value='" . $row['team_id'] . "'>" . $row['team'] . "</option>";
       }
       mysqli_free_result($result);

    }         
    ?>
</select>       
</p>

<br>
<input type="submit" name="submit1" value="Get Results"/>
</form>

最佳答案

注意：因为我使用面向对象编程，所以我永远不会像在项目中那样解决这个问题。但是，如果你要走程序路线，好吧，让我看看我能做些什么来帮助你。
这是很长的一段路，但是如果您按照下面问题中我的答案的链接，您将看到我是如何模块化（使用函数）使用sql（my sql i等）创建动态php的。
Modularizing Procedural PHP with SQL for dynamic HTML
在这种情况下，程序员希望创建一个动态的<table>，但我相信如果您需要，您可以为您的特定情况挑选一些想法。一定要把我的答案搞清楚。
对于您的问题，我更改了查询的执行方式。MySQLi::query而不是MySQLi::multi_query。此外，我还改变了处理结果（mysqli_result）的方式。
我看到你在使用MySQLi::multi_query。您的存储过程是多重查询吗？如果是这样，您可能还需要使用while（检查更多结果，返回MySQi::more_results）、bool和MySQi::next_result）添加一个小算法（MySQi::store_result循环）。
从php手册：mysqli::multi_query
示例1（处理多个查询）

if ($mysqli->multi_query($sql)) {  // Run the multi-query
    do {
        if ($result = $mysqli->store_result()) {    // Access the result.
            while ($row = $result->fetch_assoc()) { // Use the result.
               //Your code here
            }
            $result->free();
        }
    } while ($mysqli->next_result());        //Get the next result.
}

<form method="post" action="">
    <label>Years: 
        <select name="years">
        <?php 
            require_once('../../../mysqlconnect_mysqli.php');   
            $sql = 'CALL ref_sp_Year_Ref()';
            $result = $dbh->query($sql);

            if($result === false) {
                throw new UnexpectedValueException("The stored proceedure ref_sp_Year_Ref() did not return a mysqli_result object.");
            }

            while ($row = $result->fetch_assoc($result,MYSQLI_ASSOC)) {
                echo "<option value=\"{$row['year_id']}\">{$row['year']}</option>";  
            }

            $result->free();
        ?>
        </select>       
    </label>

    <label>Teams: 
        <select name="teams">
        <?php     
            $sql = 'CALL ref_sp_Team_Ref()';      
            $result = $dbh->query($sql);

            if($result === false) {
                throw new UnexpectedValueException("The stored proceedure ref_sp_Team_Ref() did not return a mysqli_result object.");
            }

            while ($row = $result->fetch_assoc()) {
                echo "<option value=\"{$row['team_id']}\">{$row['team']}</option>";
            }

            $result->free();
        ?>
        </select>       
    </label>
    <br>
    <input type="submit" name="submit1" value="Get Results"/>
</form>

/**
 * Returns a mysqli_result object, or throws an `UnexpectedValueException`.
 * You can reuse this for other SELECT, SHOW, DESCRIBE or EXPLAIN queries.
 */
function getMySQLiResult(MySQLi $db, $sql)
{
    if (!is_string($sql)) {
        throw new InvalidArgumentException("The second argument to the function getMySQLiResult must be a string (SQL query)!");
    }

    $result = $db->query($sql);

    if (!($result instanceof mysqli_result)) {
        throw new UnexpectedValueException("<p>MySQLi error no {$db->errno} : {$db->error}</p>");
    } 

    return $result;
}

/**
 * Returns a MySQLI object, or throws an `UnexpectedValueException`.
 */
function getMySQLi()
{
    require_once 'dbCreds.php'; //Choose your own file name. Do not put in public directory.

    $db = new mysqli($host, $username, $passwd, $dbname); //$port would be next.

    if (!($db instanceof MySQLi)) {
        throw new UnexpectedValueException("A MySQLi object was not returned during your connection attempt.");
    }

    if (isset($db->connect_error)) {
        throw new UnexpectedValueException("The database connection was not established. {$db->connect_errno} : {$db->connect_error}");
    }

    return $db
}

/**
 * Returns null, or an array of mysqli_result objects.
 */
function gatherMQResults(MySQLi $db, $sql)
{
    $results = []; //PHP 5.4+

    if ($db->multi_query($sql)) {  // Run the multi-query
        do {
               $result = $db->store_result();  //Store result.

               if ($result !== false) { //Test result
                   $results[] = $result //Be careful when result set is large!!
               }
        } while ($db->next_result()); //Get the next result.
    }

    return (empty($results)) ? null : $results;
}

/**
 * Uses an anonymous function to use the query result.
 */
function useMySQLiResult(Callable $fn, mysqli_result $result)
{
    $value = $fn($result->fetch_all());  //PHP 5.3+, Where $fn is an anonymous function
    $result->free();
    return $value;
}

/* Define an anonymous function */
$makeOptions = function(array $data) {
    $options = [];

    foreach ($data as $key => $value) {
        $options[] = "<option value=\"{$key}\">{$value}</option>"
    }

    return implode("\n", $options) . "\n"
};

function drawYearOptions(MySQLi $db, Callable $fn)
{
    $sql     = "someAmazingMultiQuery";     // The multi-query.
    $results = gatherMQResults($db, $sql);  // All the results.

    if (!isset($results)) {
        throw new Exception("Where the heck are the year results? None found.");
    }

    return useMySQLiResult($fn, results[0])  // Index depends on query.
}

function drawTeamOptions(MySQLi $db, Callable $fn)
{
    $sql     = "anotherAmazingMultiQuery"; // The multi-query.
    $results = gatherMQResults($db, $sql); // All the results.

    if (!isset($results)) {
        throw new Exception("Where the heck are the team results? None found.");
    }

    return useMySQLiResult($fn, results[0]) // Index depends on query.
}

<select name="foo">
    <?= drawYearOptions($mysqli, $makeOptions); ?>
</select>

<select name="bar">
    <?= drawTeamOptions($mysqli, $makeOptions); ?>
</select>

<select name="foo">
    <?= $view->drawYearOptions(); ?>
</select>

<select name="bar">
    <?= $view->drawTeamOptions(); ?>
</select>

<select name="foo">
    <?= $this->drawYearOptions(); ?>
</select>

<select name="bar">
    <?= $this->drawTeamOptions(); ?>
</select>

关于php - HTML下拉列表使用PHP和MySQL填充，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/42728182/