Iterate through the records of a query

By using a special type of FOR loop, you can iterate through the results of a query and manipulate that data. The FOR IN loop syntax is as follows:

[<<label>>]
FOR record | row IN select_clause LOOP
   statements
END LOOP;

The record or row is assigned all the rows that result from the select clause and the loop body runs for each. An example follows:

DECLARE
    mviews RECORD;
    -- Instead, if you did:
    -- mviews cs_materialized_views%ROWTYPE;
    -- this record is ONLY usable for the cs_materialized_views table
BEGIN
    CALL cs_log('Refreshing materialized views...');
    FOR mviews IN SELECT * FROM cs_materialized_views ORDER BY sort_key LOOP
    -- Now "mviews" has one record from cs_materialized_views
        RAISE EXCEPTION, 'Can't execute SQL while processing SQL for %',
        mview.my_name;
    END LOOP;
    CALL cs_log('Done refreshing materialized views.');
    return 1;
end;

The FOR-IN EXECUTE statement is another way to iterate over records:

[<<label>>]
FOR record | row IN EXECUTE text_expression LOOP
    statements
END LOOP;