Question

I am using SQLAlchemy without the ORM, i.e. using hand-crafted SQL statements to directly interact with the backend database. I am using PG as my backend database (psycopg2 as DB driver) in this instance – I don’t know if that affects the answer.

I have statements like this,for brevity, assume that conn is a valid connection to the database:

conn.execute("INSERT INTO user (name, country_id) VALUES ('Homer', 123)")

Assume also that the user table consists of the columns (id [SERIAL PRIMARY KEY], name, country_id)

How may I obtain the id of the new user, ideally, without hitting the database again?

Answer 1

You might be able to use the RETURNING clause of the INSERT statement like this:

result = conn.execute("INSERT INTO user (name, country_id) VALUES ('Homer', 123)
                       RETURNING *")

If you only want the resulting id:

result = conn.execute("INSERT INTO user (name, country_id) VALUES ('Homer', 123)
                        RETURNING id")
[new_id] = result.fetchone()