C#中的SQL查询 [英] SQL Query in c#

问题描述

我的SQL查询可能有问题.在此查询中，我合并了4个不同的表.

I might have a problem with my SQL query. In this query I'm combining 4 different tables.

• 我有一个表courses，用于存储常规信息(course_number，course_title).
• 我有一个表employees，用于存储员工的一般信息(empname和job_id).
• 员工有工作.一名员工需要参加课程.这取决于他必须修的课程.此信息存储在表job_course(以及job_id和course_id)中.
• 如果员工完成了课程，则将其存储在表emp_courses中(包含e_id和course_id)

• I have a table courses where general information is stored (course_number, course_title).
• I have a table employees where general information of employees isstored (empname, and a job_id).
• A employee has a job. A employee needs to take courses. It depends on the job which courses he has to take. This info is stored in the table job_course (with the job_id and the course_id).
• If a employee completed a course it is stored in the table emp_courses (with the e_id and the course_id)

现在，我想搜索某个课程-当用户按下搜索按钮时，他应该得到两个不同的结果.

Now I want to search a certain course - when the user presses the search button he should get two different results.

• 第一个:在这里您可以看到哪个员工已经参加了这门课程(该查询到目前为止有效)
• 第二个:在这里您可以看到哪个员工仍需要参加该课程.因此，我需要检查员工所从事的工作以及他是否需要参加该课程.而且我也只想拥有尚未完成的内容. 那是不起作用的查询

• The first one: here you can see which employee already took this course (this query works so far)
• the second one: here you can see which employee still needs to take the course. So i need to check which job the employee has and if he needs to make that course . and also i just want to have the ones that are not completed yet. And that's the query that is not working

这里是:

OpenDb_Open("select course_number,course_title, empname from course 
INNER JOIN (job_course INNER JOIN (employee INNER JOIN emp_course  
ON emp_course.e_id<>employee.e_id) ON job_course.job_id=employee.job_id) 
ON course.course_id=job_course.course_id 
where course_number like '" + coursenumber + "'");

有人可以帮我吗?

推荐答案

员工未参加的课程.

SELECT * FROM courses
WHERE course_number IN (
    SELECT course_id FROM job_course
    WHERE course_id NOT IN (
        SELECT course_id FROM emp_courses
        WHERE emp_id = {someid}
    ) AND job_id = (
        SELECT job_id FROM employees
        WHERE emp_id = {user_input}
    )
)

哪些员工仍需要参加课程.

Which employees still need to take a course.

SELECT emp_name FROM employees
WHERE emp_id NOT IN (
    SELECT emp_id FROM emp_courses
    WHERE course_id = {user_input}
)

以上版本.

SELECT emp_name FROM employees
WHERE emp_id NOT IN (
    SELECT emp_id FROM emp_courses
    WHERE course_id = (
        SELECT course_id FROM courses
        WHERE course_number = {user_input}
    )
)

这篇关于C#中的SQL查询的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！