mysql - 溶解第二个选择语句

Question

我得到了以下查询，它也有效。

SELECT date, duration, educationDepartment, yearOfTraining, completedtasks 
FROM programm_completedtask 
WHERE date BETWEEN '2014-08-05' AND '2014-08-08' 
  AND trainee_id = 
    (SELECT id FROM programm_trainee WHERE username = 'Markus');

是否可以做任何其他事情而不是第二个选择语句？我只想选择一次。

Answer 1

使用 INNER JOIN ...

SELECT p.date, p.duration, p.educationDepartment, p.yearOfTraining, p.completedtasks 
FROM programm_completedtask as p
INNER JOIN programm_trainee as pt on p.trainee_id = pt.id AND  pt.username = 'Markus'
WHERE p.date BETWEEN '2014-08-05' AND '2014-08-08' 

或

SELECT p.date, p.duration, p.educationDepartment, p.yearOfTraining, p.completedtasks 
FROM programm_completedtask as p
INNER JOIN programm_trainee as pt on p.trainee_id = pt.id 
WHERE p.date BETWEEN '2014-08-05' AND '2014-08-08' 
AND  pt.username = 'Markus'