mysqli_fetch_field()

Have you ever wondered how PHP knows whether a piece of data in the database is a number or text? The mysqli_fetch_field() function is like an X-ray for your table. It does not return the content (e.g., the name "apple"), but tells you everything about the slot where this data is stored.

EXAMPLE

<?php
$server = "localhost";
$username = "root";
$password = "";
$database = "mysqli_database";

$connection = mysqli_connect($server, $username, $password, $database);
$query = "SELECT fruit, vegetable FROM mysqli_table";

if ($result = mysqli_query($connection, $query)) {
    // The loop iterates over all columns (fields) returned by the SELECT query
    // NOTE: The mysqli_fetch_field() function does not read data rows, 
    // but returns technical information about the column itself (metadata). 
    // Since it returns data as an object, we access it using the arrow operator -> (e.g., $field->name).
    while ($field = mysqli_fetch_field($result)) {
        echo "Information for column: " . $field->name . "<br>";
        printf("Table: %s<br>", $field->table);
        printf("Data type ID: %s<br>", $field->type);
        printf("Max length: %d<br><br>", $field->max_length);
    }
    mysqli_free_result($result);
}

mysqli_close($connection);
?>

RESULT

The result will be displayed here...

Why would you need this? Imagine you are building an automated system that needs to draw a table on its own and adjust column widths based on their length in the database. With this function, you get an object containing all these technical details. Look at everything we can find out:

name: The name of the column as defined in the database.
table: The name of the table the column comes from.
max_length: The maximum length of the data in this column for the current result set.
type: The numerical code of the data type (e.g., 3 for an integer, 253 for text).