How do you read a record from a Mnesia table?

mnesia:read/1 (or the 2-arity form naming the table explicitly) fetches all records matching a given primary key, returning a list — empty if nothing matches, one element for a set table, or possibly several for a bag table where duplicate keys are allowed.

mnesia:transaction(fun() ->
    mnesia:read({person, 1})
end).
%% -> {atomic, [#person{id = 1, name = "Ada", age = 34}]}

Like write/1, read/1 must run inside a transaction so Mnesia can apply proper locking — a read inside a transaction takes a read lock, ensuring the data can't change underneath it before the transaction completes. The result of the whole transaction function is wrapped as {atomic, Result} on success, or {aborted, Reason} if it failed.

Invest now in Acorns!!! 🚀
Join Acorns and get your $5 bonus!

Acorns is a micro-investing app that automatically invests your "spare change" from daily purchases into diversified, expert-built portfolios of ETFs. It is designed for beginners, allowing you to start investing with as little as $5. The service automates saving and investing. Disclosure: I may receive a referral bonus.

Invest now!!! Get Free equity stock (US, UK only)!

Use Robinhood app to invest in stocks. It is safe and secure. Use the Referral link to claim your free stock when you sign up!.

The Robinhood app makes it easy to trade stocks, crypto and more.

Webull! Receive free stock by signing up using the link: Webull signup.