MySQL - 是一個子查詢這裏需要什麼？

Question

我現在有這樣的查詢：

SELECT 
    sec_to_time(avg(t1.sessiontime)) as aloc, 
    count(*) as calls 
FROM 
    table1 AS t1 
    inner join 
    table2 as t2 ON t1.destination = t2.prefix 
WHERE 
    t1.card_id = '101' 
AND 
    t1.terminatecauseid = 1 
group by t1.destination 

實施例的結果：

的 '呼叫' 的數據被綁定到 't1.terminatecauseid = 1'（僅應答的呼叫的意思）

我希望在所有通話中有一定比例的回答。 沒有條件的相同查詢（t1.terminatecauseid = 1）會給我所做的總調用。

我想知道什麼是添加所謂的「成功率平均爲」另一列，會做的最好辦法： 總通話*成功的呼叫/ 100 是一個子查詢這裏什麼需要？或一個全新的和不同的查詢？

Answer 1

SELECT 
    sec_to_time(avg(t1.sessiontime)) as aloc, 
    sum(t1.terminatecauseid = 1) * 100/count(*) as Average_Success_Rate, 
    sum(t1.terminatecauseid = 1) as calls 
FROM 
    table1 AS t1 
    inner join 
    table2 as t2 ON t1.destination = t2.prefix 
WHERE 
    t1.card_id = '101' 
group by t1.destination