Question

基本上我想要做的是在两个表上使用INNER JOIN，但只选择表A中的特定行和表B中的相应行？

表A被称为“课程”，我想在“course_title”栏目下选择名为“微积分”，“英国文学I”和“工作室艺术”的条目，以及相应的“department_id” ，我将使用'department_id'作为参考，为第二个表创建一个INNER JOIN，称为'departments'，其中包含'department_id'和'department_name'列。

我认为这样做的唯一方法是使用UNION来选择三个特定的课程，但是我找不到让INNER JOIN使用它的方法吗？我尝试了几种不同类型的语法并不断出错，这是我的一次尝试：

(SELECT course.course_title, cours' at line 1
mysql> (SELECT course_title, department_id FROM course WHERE course_title = 'Calculus')
-> UNION
-> (SELECT course_title, department_id FROM course WHERE course_title = 'British Literature I')
-> UNION
-> (SELECT course_title, department_id FROM course WHERE course_title = 'Studio Art I')
-> UNION
-> (SELECT department_name, department_id FROM departments)
-> FROM departments INNER JOIN course ON departments.department_id = course.department_id;

这是我的另一个尝试：

(SELECT course.course_title, course.department_id, departments.department_id, departments.department_name WHERE course.course_title = 'Calculus')
-> UNION
-> (SELECT course.course_title, course.department_id, departments.department_id, departments.department_name WHERE course.course_title = 'British Literature I')
-> UNION
-> (SELECT course.course_title, course.department_id, departments.department_id, departments.department_name WHERE course.course_title = 'Studio Art I')
-> FROM departments INNER JOIN course ON departments.department_id = course.department_id;

关于这是否有效的任何想法？如果是这样，我该如何更正我的语法？如果没有，那么另一种方法是什么？

谢谢！

Answer 1

你应该使用IN子句......

像这样

WHERE course IN ('Calculus','Physics','Art')

Answer 2

您可以像下面一样编写查询。

SELECT course.course_title, course.department_id, departments.department_id, departments.department_name 
FROM departments 
  INNER JOIN course ON departments.department_id = course.department_id
WHERE course.course_title IN ('Calculus', 'British Literature I','Studio Art I')

MySQL试图一起使用INNER JOIN和UNION？

2 个答案: