To retrieve the last inserted ID in a MySQL database using MySQLi in PHP, you can use the mysqli_insert_id() function (procedural) or the $conn->insert_id property (object-oriented). This is helpful when you want to get the ID of a newly inserted record, especially when the ID is auto-incremented.

1. Get Last Inserted ID Using MySQLi (Procedural Approach)

<?php// Database connection parameters$host = "localhost";$username = "root";$password = "";$dbname = "testDB"; // Database where the table is located// Create connection$conn = mysqli_connect($host, $username, $password, $dbname);// Check connectionif (!$conn) {    die("Connection failed: " . mysqli_connect_error());}// SQL query to insert a new record$sql = "INSERT INTO users (name, email) VALUES ('Jane Doe', 'jane@example.com')";// Execute the queryif (mysqli_query($conn, $sql)) {    // Get the last inserted ID    $last_id = mysqli_insert_id($conn);    echo "New record created successfully. Last inserted ID is: " . $last_id;} else {    echo "Error inserting record: " . mysqli_error($conn);}// Close the connectionmysqli_close($conn);?>

2. Get Last Inserted ID Using MySQLi (Object-Oriented Approach)

<?php// Database connection parameters$host = "localhost";$username = "root";$password = "";$dbname = "testDB"; // Database where the table is located// Create connection$conn = new mysqli($host, $username, $password, $dbname);// Check connectionif ($conn->connect_error) {    die("Connection failed: " . $conn->connect_error);}// SQL query to insert a new record$sql = "INSERT INTO users (name, email) VALUES ('Jane Doe', 'jane@example.com')";// Execute the queryif ($conn->query($sql) === TRUE) {    // Get the last inserted ID    $last_id = $conn->insert_id;    echo "New record created successfully. Last inserted ID is: " . $last_id;} else {    echo "Error inserting record: " . $conn->error;}// Close the connection$conn->close();?>

Explanation:

1. Database Connection:

   • We first connect to the database using either mysqli_connect() (procedural) or new mysqli() (object-oriented).

2. Insert Data:

   • We insert a new record into the users table. In this example, a record is inserted with the name "Jane Doe" and the email "jane@example.com".

3. Get Last Inserted ID:

   • After executing the INSERT query, we use:

     • Procedural: mysqli_insert_id($conn) to get the last inserted ID.

     • Object-Oriented: $conn->insert_id to retrieve the last inserted ID.

   • This will return the auto-incremented ID of the last inserted row.

4. Close the Connection:

   • Finally, the connection is closed using mysqli_close() (procedural) or $conn->close() (object-oriented).

When to Use the Last Inserted ID:

• The last inserted ID is typically used after inserting a new record with an auto-incremented primary key. For example, you may want to use this ID to associate it with other records in different tables or as part of a related operation.

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