Moodle，mysql 按课程查询用户注册状态

Question

这是 moodle 中的一个查询，用于获取课程中的校友身份。 'X'表示用户已注册，为空表示未注册。我们必须为我们拥有的每门课程添加一个子查询...... 谁能帮忙做一个更好的查询？

SELECT
    user1.firstname AS Firstname,
    user1.lastname AS Lastname,
    user1.email AS Email,
    if (exists( SELECT 
        ue.id 
        FROM mdl_user_enrolments AS ue
        JOIN mdl_enrol AS en ON en.id = ue.enrolid   
        JOIN mdl_course AS course ON course.id = en.courseid
        WHERE user1.id = ue.userid AND course.id = '1'), 'X', '') as "Enrolled Course One"
    FROM mdl_user AS user1
    LEFT JOIN mdl_user_enrolments AS ue ON ue.userid = user1.id
    LEFT JOIN mdl_enrol AS en ON en.id = ue.enrolid
    LEFT JOIN mdl_course AS course ON course.id = en.courseid
    [...]
    WHERE user1.deleted='0'

Answer 1

您可以尝试这样的操作，但如果您有很多用户和课程，则需要很长时间才能处理

    SELECT CONCAT(u.id, '_', c.id) AS uniqueid,
        u.id AS userid,
        u.firstname,
        u.lastname,
        u.email,
        MAX(CASE WHEN ue.id IS NULL THEN '' ELSE 'X' END) AS enrolled,
        c.id AS courseid,
        c.fullname AS coursename
    FROM mdl_user u
    CROSS JOIN mdl_course c
    LEFT JOIN mdl_enrol e ON e.courseid = c.id
    LEFT JOIN mdl_user_enrolments ue ON u.id = ue.userid AND ue.enrolid = e.id
    WHERE u.deleted = 0
    GROUP BY u.id, c.id

Moodle，mysql 按课程查询用户注册状态

Moodle, mysql query users enrolment status by course

mysql

moodle