高級MySQL左連接IFNULL查詢

Question

我正在尋找高級MySQL查詢的幫助。我目前的查詢，如下所示，工作正常。我想添加一個額外的字段，所以我不必創建一個單獨的查詢。新字段count（TableA.Field05）應產生TableA的總記錄數。

表A具有10個記錄
表B具有100個記錄

SELECT count(TableB.Answer) AS unAnswered 
FROM TableA 
LEFT JOIN TableB 
ON (TableA.Field01 = TableB.fkField01 AND TableA.Field02 = TableB.fkField02 AND TableB.Answer = '1') 
WHERE TableB.fkField03 IS NULL AND TableA.Field04 = 10 
GROUP BY TableA.Field01, TableA.Field02 

結果：

unAnswered = 8這是正確的

期望的結果是：

unAnswered = 8 count(TableA.Field05) = 10

-

這是一個數據和結果的例子。

SELECT count(TableB.Answer) AS unAnswered 
FROM TableA LEFT JOIN TableB ON (TableA.Field01 = TableB.fkField01 AND TableA.Field02 = TableB.fkField02 AND TableB.Answer = '1') 
WHERE TableB.fkField03 IS NULL AND TableA.Field04 = 10 
GROUP BY TableA.Field01, TableA.Field02 

TableA 
Field01 = 1, Field02 = 1, Field03 = 10 
Field01 = 1, Field02 = 2, Field03 = 21 
Field01 = 1, Field02 = 3, Field03 = 22 
Field01 = 1, Field02 = 4, Field03 = 34 

TableB 
Field01 = 1, Field02 = 1, Answer = 1 
Field01 = 1, Field02 = 2, Answer = 1 
Field01 = 1, Field02 = 3, Answer = 1 
Field01 = 2, Field02 = 1, Answer = 1 
Field01 = 2, Field02 = 2, Answer = 1 
Field01 = 2, Field02 = 3, Answer = 1 

Result 
count(TableB.Answer) AS unAnswered = 1 


Result trying to achive 
count(TableB.Answer) AS unAnswered = 1 
count(TableA.Field03) = 4 

任何幫助將不勝感激。

Answer 1

我剛想出了我自己的問題。

SELECT **COALESCE(count(DISTINCT TableB.Answer)) AS unAnswered, count(DISTINCT TableA.Field05)** 
FROM TableA 
LEFT JOIN TableB 
ON (TableA.Field01 = TableB.fkField01 AND TableA.Field02 = TableB.fkField02 AND TableB.Answer = '1') 
WHERE TableB.fkField03 IS NULL AND TableA.Field04 = 10 
GROUP BY TableA.Field01, TableA.Field02 

添加COALESCE和DISTINCT解決了我的問題。感謝大家的幫助。

Answer 2

如果你只是希望表A的數量添加到您的當前查詢只是把它添加到你的SELECT語句：

「SELECT COUNT（TableB.Answer）未答覆，計數（TableA.Field02）FROM表A ...'