But in the last record I don't have a sent record or a reciprocal accepted record; how will an inner join work?

An inner join returns only rows that have matching keys in both tables. If a row in the left table has no matching key in the right table, or vice versa, that row is omitted from the result set. In your scenario, if the last record lacks either a sent or an accepted counterpart, the inner join will exclude that record entirely. To include such rows, you would use a LEFT JOIN (to keep all rows from the left table) or a FULL OUTER JOIN (to keep all rows from both tables). For example, SELECT s., a. FROM sent s LEFT JOIN accepted a ON s.id = a.id; will return all sent records, with NULLs for missing accepted data.