如何通过存储在该列中的值访问列名

Question

I have a table its name is 'specialization' database name is 'hackathon' inside table it have one row and 8 columns "id" "name" "soft_dev" "Data_analytics" "DB_manager" "sys_engineer" "research" .networks_admin" the first row data is "5, gourav, 59.7,72.6,73.87,59.14,43.14,50.74" these are values respectively now.I am on $row['Data_analytics'] means I can access value 72.6 now I want to find out the name of this column in which it is stored Like the name is "Data_analytics". I want this value to be return how we can do it

<?php
$value = 72.6; // the value you have access to
// Connect to the database
$db = new mysqli("localhost", "root", "", "hackathon");
// Prepare the query
$query = "SELECT COLUMN_NAME FROM information_schema.columns 
WHERE table_name = 'specialization' AND table_schema = 'hackathon' 
AND (column_name LIKE 'soft_dev' OR column_name LIKE 'Data_analytics' OR column_name LIKE 'DB_manager' OR column_name LIKE 'sys_engineer' OR column_name LIKE 'research' OR column_name LIKE 'networks_admin') 
AND EXISTS (SELECT * FROM specialization WHERE Data_analytics = ?)";
$stmt = $db->prepare($query);
$stmt->bind_param("d", $value);
$stmt->execute();
// Retrieve the result
$result = $stmt->get_result();
$row = $result->fetch_assoc();
// Get the column name
$column_name = $row['COLUMN_NAME'];
echo "The value " . $value . " is stored in the column " . $column_name;
$stmt->close();
$db->close();
?>

Its giving error saying trying to access null variable or null value when i print column name

Answer 1

You're not checking if the result set is empty, or even if it has multiple rows.

Use this pattern in general...

while($row = $result->fetch_assoc())
{
    $column_name = $row['COLUMN_NAME'];
    echo "The value " . $value . " is stored in the column " . $column_name;
}

Or...

if ($result->num_rows === 0) {
    echo 'No results';
} else {
    while ($row = $result->fetch_object()) {
        $column_name = $row['COLUMN_NAME'];
        echo "The value " . $value . " is stored in the column " . $column_name;
    }
}