如何加快多个连接的SQL查询执行速度？

Question

我正在使用MySql数据库.我需要将多个(超过10个)表格中的信息合并为一个表格.为了做到这一点,我遵循典型的加入方式.

Select * from 
table_1 
Join table_2
on(table_1.id = table_2.id)
Join table_3
on(table_1.id = table_3.id)

它有效,但在执行期间我受了很多苦.有没有其他好方法来优化我的代码？以下是我的代码示例:

SELECT
distinct 
u.Id, 
oc.dt,
Daily_Number_Outgoing_Calls,     
Daily_Number_Incoming_Calls,    
Daily_duration_Outgoing_Calls

FROM
creditfix.users u

JOIN

#1 Daily_No_Out_Calls
    (
        SELECT
        cl.uId,SUBSTRING(DATE,1,10) as dt,
        count(1) as Daily_Number_Outgoing_Calls

        From creditfix.call_logs as cl
            WHERE
                cl.`type`=2 #out going calls only
        GROUP by cl.uId,dt
    ) oc
    ON (u.Id=oc.Uid)

#2 Daily_No_In_Calls
    JOIN
    (
        SELECT
        cl.uId, SUBSTRING(DATE,1,10) as dt,
        count(1) as Daily_Number_Incoming_Calls
        From creditfix.call_logs as cl
        WHERE
            cl.`type`=1 #incoming calls only
        GROUP by cl.uId,dt
    ) ic
    ON (u.Id=ic.Uid)

#3 Daily_duration_Out_Calls
     JOIN
    (
        SELECT
        cl.uId,SUBSTRING(DATE,1,10) as dt, 
        (sum(duration)) as Daily_duration_Outgoing_Calls
        From creditfix.call_logs as cl
        WHERE
            cl.`type`=2 #out going calls only
        GROUP by cl.uId,dt
    ) od
    ON (u.Id=od.uid)
    # It goes on like this...

Answer 1

看起来您不需要为每个列使用单独的子查询,您应该能够在单个子查询中执行它们.

我也认为你不应该DISTINCT在主查询中需要.

SELECT 
    u.Id, 
    cl.dt,
    cl.Daily_Number_Outgoing_Calls,     
    cl.Daily_Number_Incoming_Calls,    
    cl.Daily_duration_Outgoing_Calls,   
    cl.Daily_duration_Incoming_Calls #.... for keep on adding like this

FROM creditfix.users u
JOIN (
    SELECT uId, SUBSTRING(DATE, 1, 10) AS dt,
        SUM(`type`=2) AS Daily_Number_Outgoing_Calls,
        SUM(`type`=1) AS Daily_Number_Incoming_Calls,
        SUM(IF(`type`=2, duration, 0)) AS Daily_duration_Outgoing_Calls,
        SUM(IF(`type`=1, duration, 0)) AS Daily_duration_Incoming_Calls
    FROM creditfix.call_logs as cl
    GROUP BY uId, dt) AS cl
ON u.Id = cl.uId

查看多个查询相同的表但在不同的列mysql中查找子查询中使用的逻辑以获取所有计数.