group by clause ; visual representation
If use 'group by', set will be divided to subgroups.
implements
CREATE TABLE membeers ( name text, age integer, home text ); -- abbreviated insertion... SELECT * FROM members; name | age | home ---------+-----+--------- shimano | 25 | tottori kitano | 32 | tottori hattori | 22 | osaka sugino | 23 | hyogo mishima | 28 | hyogo hirano | 28 | osaka sato | 33 | tottori SELECT home, TRUNC(AVG(age), 1) as age_avg FROM members GROUP BY (home); home | age_avg ---------+--------- osaka | 25.0 tottori | 30.0 hyogo | 25.5
reference
thanks for your lecture.