Mysql的有條件的情況下查詢 - 找出每個條件有多少行返回

Question

請看一看這個條件MySQL查詢：

SELECT attr1,attr2,attr3 FROM table 
WHERE 
(attr1 LIKE '%cond1%' OR attr1 LIKE '%cond2%') 
OR 
(attr2 BETWEEN '30' AND '45') 
OR 
(attr3 IN ('cond3') AND attr3 = 'cond4' AND attr3 BETWEEN '18' AND '30') 
ORDER BY CASE 
WHEN (attr1 LIKE '%cond1%' OR attr1 LIKE '%cond2%') THEN 1 
WHEN (attr2 BETWEEN '30' AND '45') THEN 2 
ELSE 3 
END 

有沒有一種方法，我可以與MySQL和PHP獲得的行數每個條件回報？或者在租約條件3？

我需要一種方法來知道條件3返回了200行，例如將這個值存儲到一個php變量中。

Answer 1

可以使用CASE WHEN ... THEN ... ELSE ... ENDSUM（或COUNT使用NULL作爲ELSE結果）以SELECT的表達。使用您在上面給出的例子，你會做這樣的事情：

SELECT 
    SUM(CASE WHEN attr1 LIKE '%cond1%' OR attr1 LIKE '%cond2%' THEN 1 ELSE 0 END) AS condition1count, 
    SUM(CASE WHEN attr2 BETWEEN '30' AND '45' THEN 1 ELSE 0 END) AS condition2count, 
    SUM(CASE WHEN attr3 IN ('cond3') AND attr3 = 'cond4' AND attr3 BETWEEN '18' AND '30' THEN 1 ELSE 0 END) AS condition3count 
FROM 
    table 
... 

請記住，但是，根據數據的內容中的某些行可以匹配的3個條件多於一個，等等這3個計數的總和可能大於返回的行數。