PHP PDO::lastInsertId() Method: Usage and Examples

Returns the last inserted identifier or sequence value for the connection where supported.

The objective is to understand the behavior and operational limits, not only the method name.

What It Does

Returns the last inserted identifier or sequence value for the connection where supported.

Syntax and Return Value

PDO::lastInsertId(Parameter #0 [ <optional> ?string $name = null ]): mixed

The return value and exceptional cases depend on the call described here: Behavior is driver-specific, and PostgreSQL may require a sequence name; read before another insert.

Example 1: Basic Use

This self-contained SQLite example uses in-memory demo data; it requires the pdo_sqlite driver.

<?php
$pdo = new PDO('sqlite::memory:', null, null, [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]);
$pdo->exec('CREATE TABLE products (id INTEGER PRIMARY KEY, name TEXT NOT NULL, price INTEGER NOT NULL, active INTEGER)');
$pdo->exec("INSERT INTO products (id,name,price,active) VALUES (1,'Desk',120,1),(2,'Lamp',35,1),(3,'Chair',85,0)");
$pdo->prepare("INSERT INTO products (name,price,active) VALUES (?, ?, ?)")->execute(["Shelf 1",48,1]);
echo $pdo->lastInsertId();

Example 2: A Second Scenario

This self-contained SQLite example uses in-memory demo data; it requires the pdo_sqlite driver.

<?php
$pdo = new PDO('sqlite::memory:', null, null, [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]);
$pdo->exec('CREATE TABLE products (id INTEGER PRIMARY KEY, name TEXT NOT NULL, price INTEGER NOT NULL, active INTEGER)');
$pdo->exec("INSERT INTO products (id,name,price,active) VALUES (1,'Desk',120,1),(2,'Lamp',35,1),(3,'Chair',85,0)");
$pdo->prepare("INSERT INTO products (name,price,active) VALUES (?, ?, ?)")->execute(["Shelf 2",62,1]);
echo $pdo->lastInsertId();

Example 3: Practical Checks

This self-contained SQLite example uses in-memory demo data; it requires the pdo_sqlite driver.

<?php
$pdo = new PDO('sqlite::memory:', null, null, [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]);
$pdo->exec('CREATE TABLE products (id INTEGER PRIMARY KEY, name TEXT NOT NULL, price INTEGER NOT NULL, active INTEGER)');
$pdo->exec("INSERT INTO products (id,name,price,active) VALUES (1,'Desk',120,1),(2,'Lamp',35,1),(3,'Chair',85,0)");
$pdo->prepare("INSERT INTO products (name,price,active) VALUES (?, ?, ?)")->execute(["Shelf 3",79,1]);
echo $pdo->lastInsertId();

Important Behavior and Edge Cases

Behavior is driver-specific, and PostgreSQL may require a sequence name; read before another insert.

For production use, also account for error handling, data validation, resource limits and environment-specific driver behavior.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Returns the last inserted identifier or sequence value for the connection where supported.
• Behavior is driver-specific, and PostgreSQL may require a sequence name; read before another insert.
• RETURNING can retrieve generated keys directly in databases that support it.

Choose this API or pattern when its exact semantics match your task, and verify the result against the database driver and runtime used by your application.