下圖展示了 LEFT JOIN、RIGHT JOIN、INNER JOIN、OUTER JOIN 相關的 7 種用法。
具體分解如下：
1.INNER JOIN（內連接）
SELECT
FROM Table_A A
INNER JOIN Table_B B
ON A.Key = B.Key
2.LEFT JOIN（左連接）
SELECT
FROM Table_A A
LEFT JOIN Table_B B
ON A.Key = B.Key
3.RIGHT JOIN（右連接）
SELECT
FROM Table_A A
RIGHT JOIN Table_B B
ON A.Key = B.Key
4.OUTER JOIN（外連接）
SELECT
FROM Table_A A
FULL OUTER JOIN Table_B B
ON A.Key = B.Key
5.LEFT JOIN EXCLUDING INNER JOIN（左連接-內連接）
SELECT
FROM Table_A A
LEFT JOIN Table_B B
ON A.Key = B.Key
WHERE B.Key IS NULL
6.RIGHT JOIN EXCLUDING INNER JOIN（右連接-內連接）
SELECT
FROM Table_A A
RIGHT JOIN Table_B B
ON A.Key = B.Key
WHERE A.Key IS NULL
7.OUTER JOIN EXCLUDING INNER JOIN（外連接-內連接）
SELECT
FROM Table_A A
FULL OUTER JOIN Table_B B
ON A.Key = B.Key
WHERE A.Key IS NULL OR B.Key IS NULL