last_insert_rowid Function in SQLite

In SQLite, the last_insert_rowid() function is a special function used to retrieve the ROWID or the integer primary key value of the most recent row inserted into a table with an automatically incrementing primary key.

Here's how you can use it:

-- Create a table

CREATE TABLE users (

    id INTEGER PRIMARY KEY AUTOINCREMENT,

    username TEXT,

    email TEXT

);

-- Insert a row into the table

INSERT INTO users (username, email) VALUES ('john_doe', 'john@example.com');

-- Retrieve the ID of the last inserted row

SELECT last_insert_rowid();

In this example:

- We create a table named users with three columns: id, username, and email. The id column is specified as an INTEGER PRIMARY KEY AUTOINCREMENT, which means it will automatically increment with each new row added, and its values will be unique.

- We insert a row into the users table with a specified username and email.

- We use the last_insert_rowid() function to retrieve the id of the most recently inserted row. This function returns the value of the id column for the row that was last inserted into a table with an automatically incrementing primary key.

It's worth noting that last_insert_rowid() is connection-specific. This means that it will return the last inserted row ID for the current database connection. If you have multiple connections to the database, each connection will have its own "last inserted row ID" value. Additionally, this function only works for tables with an integer primary key that uses AUTOINCREMENT. If the table has a composite key or a primary key that's not auto-incrementing, this function will not return the desired result.

Here are five frequently asked questions (FAQs) about the last_insert_rowid() function in SQLite along with brief answers:-

1. What is the last_insert_rowid() function in SQLite?

   The last_insert_rowid() function in SQLite is a special function that returns the ROWID or the integer primary key value of the most recent row inserted into a table with an automatically incrementing primary key.

2. How does last_insert_rowid() work?

   After an INSERT statement is executed on a table with an automatically incrementing primary key, the last_insert_rowid() function can be called to retrieve the value of the primary key for the most recently inserted row within the current database connection.

3. Is last_insert_rowid() connection-specific?

   Yes, last_insert_rowid() is connection-specific. It returns the last inserted row ID for the current database connection. If you have multiple connections to the database, each connection will have its own "last inserted row ID" value.

4. Can last_insert_rowid() be used with tables that have composite keys?

   No, last_insert_rowid() cannot be used with tables that have composite keys or primary keys that are not auto-incrementing. It specifically works for tables with a single auto-incrementing integer primary key.

5. What happens if last_insert_rowid() is called after a DELETE or UPDATE operation?

   If last_insert_rowid() is called after a DELETE or UPDATE operation, it will return the last inserted row ID within the current database connection, regardless of any intervening DELETE or UPDATE operations. However, it's important to note that last_insert_rowid() is typically used after an INSERT operation to retrieve the ID of the newly inserted row.