Question

我有以下MySQL表：

+--------------------+----------+------+-----+---------+----------------+
| Field              | Type     | Null | Key | Default | Extra          |
+--------------------+----------+------+-----+---------+----------------+
| id                 | int(11)  | NO   | PRI | NULL    | auto_increment |
| firstName          | longtext | NO   |     | NULL    |                |
| lastName           | longtext | NO   |     | NULL    |                |
| username           | longtext | NO   |     | NULL    |                |
+--------------------+----------+------+-----+---------+----------------+

和

+------------------------+----------+------+-----+---------+----------------+
| Field                  | Type     | Null | Key | Default | Extra          |
+------------------------+----------+------+-----+---------+----------------+
| id                     | int(11)  | NO   | PRI | NULL    | auto_increment |
| trainee_id             | int(11)  | NO   | MUL | NULL    |                |
| date                   | date     | NO   |     | NULL    |                |
| duration               | time     | NO   |     | NULL    |                |
| educationDepartment    | longtext | NO   |     | NULL    |                |
| completedtasks         | longtext | NO   |     | NULL    |                |
+------------------------+----------+------+-----+---------+----------------+

我有两个条件。我从第二个表开始和结束日期，我想要一个特定用户的数据，我可以通过＆＃34;用户名＆＃34;第一张桌子。它看起来像这样：用户名已知＆gt;我将获得用户的id（外键）＆gt;现在，我可以使用此外键从第二个表中获取用户特定的数据。我开始我的MySQL查询，它看起来像这个atm：

SELECT date, duration, educationDepartment, completedtasks FROM programm_completedtask WHERE date BETWEEN "2014-04-07" AND "2014-04-11";

但是我现在如何才能使用它？重要提示：我只想要一个MySQL查询，php或类似的东西不能帮助我：/

Answer 1

这样的东西？

SELECT table2.username, table1.date, table1.duration, table1.educationDepartment, table1.completedtasks FROM table1 LEFT JOIN table2 ON table2.id = table1.trainee_id WHERE table1.date BETWEEN "2014-04-07" AND "2014-04-11" AND table1.username = 'someuser';

Answer 2

这会将结果限制为一个特定用户：

SELECT date, duration, educationDepartment, completedtasks 
FROM programm_completedtask 
WHERE date BETWEEN '2014-04-07' AND '2014-04-11'
AND trainee_id = (select id from users where username = 'XYZ');

Answer 3

如果您想从两个表中获得结果，您应该使用INNER JOIN：

SELECT u.username, p.date, p.duration, p.educationDepartment, p.completedtasks 
FROM programm_completedtask AS p
INNER JOIN users AS u ON u.id = p.trainee_id
WHERE date BETWEEN "2014-04-07" AND "2014-04-11"
AND u.username = "knownusername";

MySQL查询，您无法通过联接访问关系

3 个答案: