Question

很难解释，我的英语没有帮助，但它是：我有两个数据表：“节点”和“记录”。在节点表中，我保存了问题数据和答案数据

节点： | id |名字|类型|

记录： | id | questionid | answerid |

我试过尽管没有成功，但是做一个sql查询给了我所有记录的数据，但是带有答案的名称和id的问题内容。简而言之，我需要的是：records.id，nodes.name（question），nodes.name（answer）

Answer 1

SELECT
  questions.name AS questionname
  answers.name AS answername
FROM records
  INNER JOIN nodes AS questions ON records.questionid=questions.id
  INNER JOIN nodes AS answers ON records.answerid=answers.id

Answer 2

您可以使用此查询：

SELECT q.name AS question, a.name AS answer
FROM records r 
LEFT JOIN nodes q ON q.id = r.questionid
LEFT JOIN nodes a ON a.id = r.answerid
WHERE 1

对于此查询，我在下面构建架构：

CREATE TABLE nodes (
 id int auto_increment primary key, 
 name varchar(30),
 type int(1));

INSERT INTO nodes (name, type) VALUES
('Is it a question 01', 0),
('Is it a question 02', 0),
('This is an answer 01', 1),
('This is an answer 02', 1),
('This is an answer 03', 1);

CREATE TABLE records (
 id int auto_increment primary key, 
 questionid int(11),
 answerid int(11));

INSERT INTO records (questionid, answerid) VALUES
(1, 3), (1, 4), (1, 5), (2, 4), (2, 5);

SQL小提琴：http://sqlfiddle.com/#!2/bfd340/1

sql查询从另一个数据表中加入不同数据的数据表

2 个答案: