null /空白を返さない複数テーブル結合でのヘルプ

Question

同じスキーマを持ち、3つの異なるソースからの同様の結果を含む3つのテーブル（s_place、s_place_bing、s_place_yahoo）があります。私が望むのは、与えられたs_u_id、s_q_idおよび日付と一致する3つのテーブルからすべての結果を返すクエリです。

+-----------------+--------------+------+-----+---------+----------------+ 
| Field   | Type   | Null | Key | Default | Extra   | 
+-----------------+--------------+------+-----+---------+----------------+ 
| id    | int(10)  | NO | PRI | NULL | auto_increment | 
| s_u_id   | int(10)  | NO |  | NULL |    | 
| s_q_id   | int(10)  | NO |  | NULL |    | 
| place   | int(10)  | NO |  | NULL |    | 
| date   | int(10)  | YES |  | NULL |    | 
| fullurl   | varchar(255) | NO |  | NULL |    | 
| above_today  | varchar(255) | NO |  | NULL |    | 
| above_yesterday | varchar(255) | NO |  | NULL |    | 
| below_today  | varchar(255) | NO |  | NULL |    | 
| below_yesterday | varchar(255) | NO |  | NULL |    | 
| yesterday  | int(11)  | NO |  | NULL |    | 
+-----------------+--------------+------+-----+---------+----------------+ 

それは同じs_u_id、s_q_idと日付の他にあるよりも、一つのテーブルでより多くの結果があるだろうということは非常に可能性があります。この場合、データを持たないテーブルに対しては空白の行が返されます。

これまでのところ、以下のクエリを使用していますが、null /空白は返されません。

SELECT s_place.s_u_id, s_place.s_q_id, `s_place`.place as place, `s_place`.fullurl as fullurl, `s_place`.date as date, s_place_bing.place as b_place,`s_place_bing`.fullurl as b_fullurl, s_place_bing.date as b_date, s_place_yahoo.place as y_place, `s_place_yahoo`.fullurl as y_fullurl, s_place_yahoo.date as y_date 
from s_place 
left join s_place_bing on s_place_bing.s_q_id = s_place.s_q_id and s_place_bing.date = s_place.date 
left join s_place_yahoo on s_place_yahoo.s_q_id = s_place.s_q_id and s_place_yahoo.date = s_place.date 
where s_place.s_u_id = 1 and s_place.s_q_id = 64 
order by s_place.date desc 

+--------+--------+-------+----------------------+------------+---------+--------------------------+------------+---------+-------------------+------------+ 
| s_u_id | s_q_id | place | fullurl    | date  | b_place | b_fullurl    | b_date  | y_place | y_fullurl   | y_date  | 
+--------+--------+-------+----------------------+------------+---------+--------------------------+------------+---------+-------------------+------------+ 
|  1 |  64 | 39 |  rrr.co.uk  | 1292112000 |  30 |  rrr.co.uk   | 1292112000 |  6 |  rrr.co.uk | 1292112000 | 
|  1 |  64 | 39 |  rrr.co.uk  | 1292112000 |  65 |  rrr.co.uk search/ | 1292112000 |  6 |  rrr.co.uk | 1292112000 | 
|  1 |  64 | 36 |  rrr.co.uk  | 1292025600 |  30 |  rrr.co.uk   | 1292025600 |  6 |  rrr.co.uk | 1292025600 | 
|  1 |  64 | 36 |  rrr.co.uk  | 1292025600 |  64 |  rrr.co.uk search/ | 1292025600 |  6 |  rrr.co.uk | 1292025600 | 
|  1 |  64 | 40 |  rrr.co.uk  | 1291939200 |  66 |  rrr.co.uk search/ | 1291939200 | 9999 |     | 1291939200 | 
|  1 |  64 | 40 |  rrr.co.uk  | 1291939200 |  29 |  rrr.co.uk   | 1291939200 | 9999 |     | 1291939200 | 
|  1 |  64 | 38 |  rrr.co.uk  | 1291852800 |  29 |  rrr.co.uk   | 1291852800 |  6 |  rrr.co.uk | 1291852800 | 
|  1 |  64 | 38 |  rrr.co.uk  | 1291852800 |  68 |  rrr.co.uk search/ | 1291852800 |  6 |  rrr.co.uk | 1291852800 | 

これはデータを返さなければならない方法です。

+--------+--------+-------+----------------------+------------+---------+--------------------------+------------+---------+-------------------+------------+ 
| s_u_id | s_q_id | place | fullurl    | date  | b_place | b_fullurl    | b_date  | y_place | y_fullurl   | y_date  | 
+--------+--------+-------+----------------------+------------+---------+--------------------------+------------+---------+-------------------+------------+ 
|  1 |  4 | 39 |  rrr.co.uk  | 1292112000 |  30 |  rrr.co.uk   | 1292112000 |  6 |  rrr.co.uk | 1292112000 | 
|  1 |  64 |  |      |   |  65 |  rrr.co.uk search/ | 1292112000 |   |     |   | 
|  1 |  64 | 36 |  rrr.co.uk  | 1292025600 |  30 |  rrr.co.uk   | 1292025600 |  6 |  rrr.co.uk | 1292025600 | 
|  1 |  64 |  |      |   |  64 |  rrr.co.uk search/ | 1292025600 |   |     |   | 
|  1 |  64 | 40 |  rrr.co.uk  | 1291939200 |  66 |  rrr.co.uk search/ | 1291939200 | 9999 |     | 1291939200 | 
|  1 |  64 |  |      |   |  29 |  rrr.co.uk   | 1291939200 |   |     |   | 
|  1 |  64 | 38 |  rrr.co.uk  | 1291852800 |  29 |  rrr.co.uk   | 1291852800 |  6 |  rrr.co.uk | 1291852800 | 
|  1 |  64 |  |      |   |  68 |  rrr.co.uk search/ | 1291852800 |   |     |   | 

誰かが助けてくれることを願っています。乾杯、

Answer 1

希望する結果セットでは、完全に入力された列はs_place_bingテーブルからのものであることに注意してください。したがって、結果セットから、 s_placeとs_place_yahooテーブルをs_place_bingテーブルに追加する必要があります。

あなたの現在のクエリはs_place.date descでソートされていますが、希望する結果セットにはそのフィールドに空の/ヌルがあります。

これはあなたの望む結果をもたらしますか？

SELECT 
    b.s_u_id, b.s_q_id, 
    p.place AS p_place, p.fullurl AS p_fullurl, p.date AS p_date, 
    b.place AS b_place, b.fullurl AS b_fullurl, b.date AS b_date, 
    y.place AS y_place, y.fullurl AS y_fullurl, y.date AS y_date 
FROM s_place_bing b 
LEFT JOIN s_place p ON b.s_q_id = p.s_q_id AND b.date = p.date 
LEFT JOIN s_place_yahoo y ON b.s_q_id = y.s_q_id AND b.date = y.date 
WHERE b.s_u_id = 1 and b.s_q_id = 64 
ORDER BY b.date DESC