有一个person表,主键是id,如下:
有一个任务(task)表如下,主键也是id,如下:
请你找到每个人的任务情况,并且输出出来,没有任务的也要输出,而且输出结果按照person的id升序排序,输出情况如下:
drop table if exists person; drop table if exists task; CREATE TABLE `person` ( `id` int(4) NOT NULL, `name` varchar(32) NOT NULL, PRIMARY KEY (`id`)); CREATE TABLE `task` ( `id` int(4) NOT NULL, `person_id` int(4) NOT NULL, `content` varchar(32) NOT NULL, PRIMARY KEY (`id`)); INSERT INTO person VALUES (1,'fh'), (2,'tm'); INSERT INTO task VALUES (1,2,'tm works well'), (2,2,'tm works well');
解题
SELECT p.id, p.name, t.content FROM person AS p LEFT JOIN task AS t ON p.id = t.person_id;