我正在编写一个脚本，该脚本本质上是将数据从 API 加载到本地 MySQL 数据库中。这些值根据 API 返回的内容而变化。

到目前为止，一切都工作正常，直到我尝试将行实际插入 MySQL 数据库。具体来说，我知道我应该使用准备好的语句，但是当我尝试将变量绑定到准备好的语句时遇到了麻烦。当我尝试运行以下代码时，我得到：

PHP Warning:  mysqli_stmt::bind_param(): Number of elements in type definition string doesn't match number of bind variables in /opt/awn2sql/functions.php on line 212

这是有问题的代码：

$readingValues = array_values($read); //array of just the values in the original array
array_push($readingValues, $devicemac); //add the MAC address of the device that recorded the reading to the array
    
$columns = implode(", ",$readingTypes); //create a string of column names to build the SQL query
    
$valuesCount = count($readingValues); //get a count of the values to fill an array with placeholders
$stmt_placeholders = implode(',',array_fill(0,$valuesCount,'?')); //fill an array with placeholders (i.e. ?,?,?) - see above
$stmt_param = null; //$stmt_param will hold the type definitions string for binding the 
    
foreach ($readingValues as $param) { //iterate through each value in the $readingValues array, get the type, and add it to the type definitions string
    if (gettype($param) == 'integer')
    {
        $stmt_param = $stmt_param.'i';
    }
    else if (gettype($param) == 'double')
    {
        $stmt_param = $stmt_param.'d';
    }               
    else if (gettype($param) == 'string')
    {
    $stmt_param = $stmt_param.'s';
    }
    else if (gettype($param) == 'blob')
    {
        $stmt_param = $stmt_param.'b';
    }
    else
    {
        echo "Invalid data type!";
    }
}

$val_insert_query = "INSERT INTO ".$config['mysql_db'].".readings (".$columns.") VALUES (".$stmt_placeholders.");"; //Template for the query
    
$stmt=$mysqli->prepare($val_insert_query); //Prepares the template for the query for binding, prepared statement becomes $stmt

echo ($stmt_param." (".strlen($stmt_param).")\n"); //for debugging, echo the type definiton string and get its length (which should match the number of values)

echo (count($readingValues)); //count the number of values, which should match the number of elements in the type defintion string
    
$stmt->bind_param($stmt_param, $readingValues); //Binding
    
$stmt->execute(); //execute the statement

我坦率地承认我在这方面有点新手，所以我愿意接受任何关于如何做得更好的建议。就其价值而言，从来没有任何直接的用户输入，所以我相对不关心安全问题，如果这对如何最好地解决这个问题有影响的话。

提前致谢！