Mysql: Все в одном запросе

Question

У меня есть 3 запросов, работающих совершенно

SELECT snapdate, COUNT(DISTINCT uid) AS t1 
FROM table where tid =1 
GROUP BY snapdate 
ORDER BY snapdate DESC LIMIT 7 

Запрос # 1:

snapdate  t1 
----------  -- 
2013-07-02  10 
2013-07-01  20 
2013-06-30  60 
2013-06-29  80 
2013-06-28  3 
2013-06-27  22 
2013-06-26  93 

Запрос # 2:

SELECT snapdate, COUNT(DISTINCT uid) AS t2 
FROM table where tid =2 
GROUP BY snapdate 
ORDER BY snapdate DESC LIMIT 7 

snapdate  t2 
----------  -- 
2013-07-02  35 
2013-07-01  52 
2013-06-30  69 
2013-06-29  75 
2013-06-28  91 
2013-06-27  97 
2013-06-26  93 

Запрос # 3:

SELECT snapdate, COUNT(DISTINCT uid) AS t3 
FROM table where tid =3 
GROUP BY snapdate 
ORDER BY snapdate DESC LIMIT 7 

snapdate  t3 
----------  -- 
2013-07-02  22 
2013-07-01  22 
2013-06-30  26 
2013-06-29  27 
2013-06-28  29 
2013-06-27  29 
2013-06-26  29 

Но я не знаю, как иметь 3 результатов все вместе

snapdate  t1 t2 t3 
----------  -- -- -- 
2013-07-02  10 35 22 
2013-07-01  20 52 22 
2013-06-30  60 69 26 
2013-06-29  80 75 27 
2013-06-28  3 91 29 
2013-06-27  22 97 29 
2013-06-26  93 93 29 

Answer 1

Вы можете использовать выражение CASE, внутри вашей агрегатной функции:

SELECT snapdate, 
    COUNT(DISTINCT case when tid =1 then uid end) AS t1, 
    COUNT(DISTINCT case when tid =2 then uid end) AS t2, 
    COUNT(DISTINCT case when tid =3 then uid end) AS t3 
FROM table 
GROUP BY snapdate 
ORDER BY snapdate DESC 
LIMIT 7