高级MySQL左连接IFNULL查询

Question

我正在寻找高级MySQL查询的帮助。我目前的查询，如下所示，工作正常。我想添加一个额外的字段，所以我不必创建一个单独的查询。新字段count（TableA.Field05）应产生TableA的总记录数。

表A具有10个记录
表B具有100个记录

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 

结果：

unAnswered = 8这是正确的

期望的结果是：

unAnswered = 8 count(TableA.Field05) = 10

-

这是一个数据和结果的例子。

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 

任何帮助将不胜感激。

Answer 1

我刚想出了我自己的问题。

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解决了我的问题。感谢大家的帮助。

Answer 2

如果你只是希望表A的数量添加到您的当前查询只是把它添加到你的SELECT语句：

“SELECT COUNT（TableB.Answer）未答复，计数（TableA.Field02）FROM表A ...'