Get last record of a table in Postgres

I’m using Postgres and cannot manage to get the last record of my table:

 my_query = client.query("SELECT timestamp,value,card from my_table");

How can I do that knowning that timestamp is a unique identifier of the record ?

Answer

If under “last record” you mean the record which has the latest timestamp value, then try this:

my_query = client.query("
  SELECT TIMESTAMP,
    value,
    card
  FROM my_table
  ORDER BY TIMESTAMP DESC
  LIMIT 1
");