Mysql SQL命令对多列的结果进行计数？

考虑以下名为“calls”的SQL表，该表是John电话账单中电话的完整列表：

Sample Data Set for a Call log:
from, to, length (min)
John, Jill, 15
John, Jill, 7
Jill, John, 4
John, Jill, 6
John, Jill, 9

我发现以下查询：

SELECT calls.from, calls.to, COUNT(1) AS call_count
FROM `mydb.calls` AS calls
WHERE calls.from = "John" OR calls.to = "John"
GROUP BY calls.from, calls.to
ORDER by call_count DESC

给我以下结果：

row, from, to, call_count
1, John, Jill, 4
2, Jill, John, 1

从John的角度来看，我真正想要的和我不知道的是如何统计入站和出站呼叫的总结果。我希望基本上显示以下内容：

row, who, inbound, outbound, total
1, Jill, 1, 4, 5

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任何帮助都将不胜感激

您可以对分组键使用条件逻辑：

SELECT (CASE WHEN c.from = 'John' THEN c.to ELSE c.from END) as who, 
       COUNT(*) AS call_count
FROM `mydb.calls` c
WHERE 'John' in (c.from, c.to)
GROUP BY who
ORDER by call_count DESC;

SELECT (CASE WHEN c.from = 'John' THEN c.to ELSE c.from END) as who, 
       COUNT(*) AS call_count,
       SUM(c.from = 'John') as inbound,
       SUM(c.to = 'John') as outbound
FROM `mydb.calls` c
WHERE 'John' in (c.from, c.to)
GROUP BY who
ORDER by call_count DESC

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太快了！去试试看。看起来确实管用！非常感谢。如何添加两个额外的列？即入出境栏目？非常感谢！你是一个偶然的自由职业者吗？仅供参考-当从BQ运行时，我必须使用SUM（CAST（c.from='John'AS INT64））作为inbound@AlwaysLearning . . . 您的问题被标记为MySQL，此代码将在MySQL中运行。