Question

我有一个MySQL查询，我想执行该查询以查看谁是我工作的公司中技能X最高的员工。为此，我从我的cv_profile（skill_cv_test）中随机选择一家公司，并找到在同一雇主那里工作的所有用户。然后，我随机选择一种技能。结果应为零或列表。但是，当用PHPMyAdmin进行测试时，我得到的结果是我看不到任何行，但是状态显示至少有一行。这是我收到的消息的示例：https://imgur.com/bVMH716

我一直在尝试不同的结构，甚至将查询与另一个查询“连接”在一起，使用不同的联接。

SELECT
DISTINCT(sv.usr_id),
u.first_name AS fn,
u.last_name AS ln,
c.name AS company,
s.name AS skill 
FROM 
    (
        SELECT 
            MAX(last_change) as date, 
            id,
            usr_id, 
            skill_id
        FROM skill_valuations 
        GROUP BY usr_id, skill_id
        ORDER BY date
    ) sv
LEFT JOIN skill_valuations skv ON skv.last_change = sv.date
INNER JOIN 
    (
        SELECT 
            DISTINCT(skct.comp_id),
            skct.usr_id AS usr_id, 
            skct.category 
        FROM skill_cv_test skct 
        WHERE skct.end_date IS NULL AND skct.comp_id IN (SELECT comp_id FROM (SELECT comp_id FROM skill_cv_test WHERE usr_id = 1 ORDER BY RAND() LIMIT 1) x)
    ) uqv ON uqv.usr_id = sv.usr_id
INNER JOIN 
    (
        SELECT skill_id 
        FROM usr_skills 
        WHERE usr_id = $uid 
        ORDER BY RAND() 
        LIMIT 1
    ) usq ON usq.skill_id = sv.skill_id 

LEFT JOIN companies c ON c.id = uqv.comp_id
LEFT JOIN skills s ON s.id = sv.skill_id
LEFT JOIN users u ON u.id = sv.usr_id

如前所述，我希望没有结果或至少有一行结果。

如何解决查询结果不显示的问题？

0 个答案: