數據庫連接查詢

1、創建兩張表

a_001表

b_001表

查詢語句：

1、內連接

SELECT * FROM a_001 INNER JOIN b_001 ON a_001.id=b_001.parent_id

2、左連接

SELECT * FROM a_001 LEFT JOIN b_001 ON a_001.id=b_001.parent_id

3、右連接

SELECT * FROM a_001 RIGHT JOIN b_001 ON a_001.id=b_001.parent_id