[データベースシステム論]　試行課題２

gistfile1.sql

--試行課題2
---以下の三つのSQLを試してみて、結果からそれぞれの問い合わせの意味・違いを考えよう。

--右結合
SELECT wid, name, district, price
  FROM wine LEFT JOIN vineyard 
  ON wine.did = vineyard.did;

--左結合
SELECT wid, name, district, price
  FROM wine RIGHT JOIN vineyard 
  ON wine.did = vineyard.did;

--全結合
SELECT wid, name, district, price
  FROM wine FULL JOIN vineyard 
  ON wine.did = vineyard.did;