複雜嗎？ MySQL Query

Question

我有一個表，列id，日期，estValue & gradeid。每個成績ID有大約12條記錄，總共約120條記錄有大約10個不同的成績[給與接受]。我需要從數據庫中創建一個選擇，它給我一個看起來像這樣的結果集：

date |gradeid1 |gradeid2 |gradeid3 3|etc... 
01/01/01|estValue1|estValue2||estValue3|etc.... 
01/01/02|estValue1|estValue2||estValue3|etc.... 

我有一個查詢，可以選擇一個記錄，但我需要他們全部按日期排序：

select eh.id, eh.date as wdate, 
    (select estValue from nas_estimatehistory where `date` like '2011-03-%' and gradeid = '1') as '1', 
    (select estValue from nas_estimatehistory where `date` like '2011-03-%' and gradeid = '2') as '2', 
    (select estValue from nas_estimatehistory where `date` like '2011-03-%' and gradeid = '3') as '3', 
    (select estValue from nas_estimatehistory where `date` like '2011-03-%' and gradeid = '4') as '4', 
    (select estValue from nas_estimatehistory where `date` like '2011-03-%' and gradeid = '5') as '5', 
    (select estValue from nas_estimatehistory where `date` like '2011-03-%' and gradeid = '6') as '6', 
    (select estValue from nas_estimatehistory where `date` like '2011-03-%' and gradeid = '7') as '7', 
    (select estValue from nas_estimatehistory where `date` like '2011-03-%' and gradeid = '8') as '8', 
    (select estValue from nas_estimatehistory where `date` like '2011-03-%' and gradeid = '9') as '9', 
    (select estValue from nas_estimatehistory where `date` like '2011-03-%' and gradeid = '10') as '10' 
from nas_estimatehistory eh 
group by wdate 
order by `wdate` asc 
limit 1; 

返回差不多就是我所需要的，但只有1行，如果我刪除了極限，然後我得到每行[12行]的一行，但所有的列值是相同的[他們應該都是不同的]，即estValue在每行和列應該是一個唯一的值...

我不確定最好的方法是什麼。

-Thanks -Sean

Answer 1

Cross-tabulation的關鍵在於：使用一個aggregate function和IF功能。

SELECT eh.date AS wdate, 
    GROUP_CONCAT(IF(gradeid=1,estValue,NULL)) as `1`, 
    GROUP_CONCAT(IF(gradeid=2,estValue,NULL)) as `2`, 
    GROUP_CONCAT(IF(gradeid=3,estValue,NULL)) as `3`, 
    GROUP_CONCAT(IF(gradeid=4,estValue,NULL)) as `4`, 
    GROUP_CONCAT(IF(gradeid=5,estValue,NULL)) as `5`, 
    GROUP_CONCAT(IF(gradeid=6,estValue,NULL)) as `6`, 
    GROUP_CONCAT(IF(gradeid=7,estValue,NULL)) as `7`, 
    GROUP_CONCAT(IF(gradeid=8,estValue,NULL)) as `8`, 
    GROUP_CONCAT(IF(gradeid=9,estValue,NULL)) as `9`, 
    GROUP_CONCAT(IF(gradeid=10,estValue,NULL)) as `10` 
FROM nas_estimatehistory eh 
GROUP BY wdate 
ORDER BY `wdate` ASC; 

MAX或MIN也可以是合適的聚集函數。

Answer 2

就像我說的，忘記該集團的一部分。它沒有效果。 我想我看到你的問題。

替換gradeid = '1' 與gradeid = eh.gradeid

Answer 3

select eh.id, wdate, 
    (select estValue from nas_estimatehistory where `date` like `pattern` and gradeid = '1') as '1', 
    (select estValue from nas_estimatehistory where `date` like `pattern` and gradeid = '2') as '2', 
    (select estValue from nas_estimatehistory where `date` like `pattern` and gradeid = '3') as '3', 
    (select estValue from nas_estimatehistory where `date` like `pattern` and gradeid = '4') as '4', 
    (select estValue from nas_estimatehistory where `date` like `pattern` and gradeid = '5') as '5', 
    (select estValue from nas_estimatehistory where `date` like `pattern` and gradeid = '6') as '6', 
    (select estValue from nas_estimatehistory where `date` like `pattern` and gradeid = '7') as '7', 
    (select estValue from nas_estimatehistory where `date` like `pattern` and gradeid = '8') as '8', 
    (select estValue from nas_estimatehistory where `date` like `pattern` and gradeid = '9') as '9', 
    (select estValue from nas_estimatehistory where `date` like `pattern` and gradeid = '10') as '10' 
from (
    select eh.*, date_format(eh.date, '%Y-%m') wdate, 
       concat(date_format(eh.date, '%Y-%m'),'-%') `pattern` 
    from nas_estimatehistory) eh 
group by wdate 
order by wdate asc;