基於在同一列

Question

這是很難形容我想的話所以這裏的表我處理

Persons 
First | Last | ID 
John | Smith | 1 
Jane | Smith | 2 

PerKey 
ID | KW | HITS 
1 | P.E. | 1 
1 | M E | 1 
1 | HVAC | 4 
2 | Acct | 7 

多種標準選擇單列我想要做的就是從人那裏選擇標準符合多行。

例如，我想知道誰有'體育' AND'M E'和'HVAC'。

在這種情況下，將返回約翰史密斯。

我已經能夠使用IN和HAVING子句完成此操作，但這限制了我無法過濾個人擁有KW和OR子句的次數。

說我只希望有人在'暖通空調'上有5次命中，這將理想地約翰史密斯。這裏的查詢我有個大氣壓：

SELECT first, last 
FROM persons 
LEFT JOIN perkey ON persons.id = perkey.id 
WHERE kw IN ('P.E.','M E','HVAC') 
GROUP BY first, last, persons.id 
HAVING COUNT(DISTINCT kw) = 3 

我使用SQL Server 2008。我無法改變的數據結構要麼因爲它是專有的。感謝您的任何幫助/建議。

Answer 1

您可以使用條件聚集以選擇性地計算每個可能kw值：

SELECT first, last, 
     COUNT(CASE WHEN kw = 'P.E.' THEN 1 END) AS PE, 
     COUNT(CASE WHEN kw = 'M E' THEN 1 END) AS ME, 
     COUNT(CASE WHEN kw = 'HVAC' THEN 1 END) AS HVAC 
FROM persons 
LEFT JOIN perkey ON persons.id = perkey.id 
WHERE kw IN ('P.E.','M E','HVAC') 
GROUP BY first, last, persons.id 
HAVING COUNT(DISTINCT kw) = 3 

編輯：

如果您想根據，說來篩選記錄，HVAC那麼您可以在HAVING子句中添加條件聚合，例如：

SELECT first, last    
FROM persons 
LEFT JOIN perkey ON persons.id = perkey.id 
WHERE kw IN ('P.E.','M E','HVAC') 
GROUP BY first, last, persons.id 
HAVING COUNT(DISTINCT kw) = 3 AND 
     COUNT(CASE WHEN kw = 'HVAC' THEN 1 END) > 5 

EDIT2：

如果您想根據hits字段的值來篩選記錄，那麼你可以使用：

SELECT first, last    
FROM persons 
LEFT JOIN perkey ON persons.id = perkey.id 
WHERE kw IN ('P.E.','M E','HVAC') 
GROUP BY first, last, persons.id 
HAVING COUNT(DISTINCT kw) = 3 AND 
     COUNT(CASE WHEN hits > 4 THEN 1 END) > 0 

Answer 2

有條件的分組應該工作，既要檢查各類千瓦，並限制或進一步檢查任何/所有類型的發生次數。像這樣：

SELECT persons.id, first, last, 
    SUM(CASE WHEN kw = 'P.E.' THEN 1 ELSE 0 END) AS PE, 
    SUM(CASE WHEN kw = 'M E' THEN 1 ELSE 0 END) AS ME, 
    SUM(CASE WHEN kw = 'HVAC' THEN 1 ELSE 0 END) AS HVAC 
FROM persons 
LEFT JOIN perkey ON persons.id = perkey.id 
WHERE kw IN ('P.E.','M E','HVAC') 
GROUP BY first, last, persons.id 
HAVING SUM(CASE WHEN kw = 'P.E.' THEN 1 ELSE 0 END) > 0 
AND SUM(CASE WHEN kw = 'M E' THEN 1 ELSE 0 END) > 0 
AND SUM(CASE WHEN kw = 'HVAC' THEN 1 ELSE 0 END) > 0