What potential issues can arise when using the LIMIT and ORDER BY clauses in a SQL query to find the last ID?

When using the LIMIT and ORDER BY clauses in a SQL query to find the last ID, potential issues can arise if the ORDER BY clause is not correctly specified. To ensure that the last ID is retrieved correctly, the ORDER BY clause should be in descending order based on the ID column. Additionally, the LIMIT clause should be set to 1 to retrieve only the last ID. 

<?php

// Connect to database
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";
$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

// SQL query to retrieve the last ID
$sql = "SELECT id FROM table_name ORDER BY id DESC LIMIT 1";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        echo "Last ID: " . $row["id"];
    }
} else {
    echo "0 results";
}

$conn->close();

?>

Keywords

SQL LIMIT ORDER BY last ID potential issues

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