检查表单发布的变量是否存在于MySql列之一中 [英] Check if form-posted variable is existing in one of MySql columns

问题描述

我有一个HTML表单，该表单发布了Class Number值Ex. 150701-003

I have a html form that posts a Class Number value Ex. 150701-003

在我的php操作文件中，我要检查变量$ class_number是否已在名为CLASS NO的MySql表列中.

In my php action file, I want to check if the variable $class_number is already in the MySql table column named CLASS NO.

$class_number = $_POST['class'];
                 echo $class_number;

                  $check_class_number = mysqli_query($con, "SELECT * FROM Academy.COLUMNS 
                  WHERE ClassNumber = '$class_number' ");

                  if(count($check_class_number)>0){
                    echo "exists";
                  }
                  else{
                  echo "It does not exist.";
                  }

推荐答案

尝试以下操作:

$result = mysqli_query($con, "SELECT * FROM Academy.COLUMNS 
                              WHERE ClassNumber = '$class_number'");

if(mysqli_num_rows($result) == 0) {
    // the number does not exist so do whatever you wish
} else {
    // post an error message
}

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