在 select 语句中的 LEFT JOIN 之前使用 WHERE 子句

Question

我有下面的代码，希望就如何在左连接之前使用 'where' 子句获得一些帮助 - 我有一个包含大量数据的 table 但需要在我 return 我想要的 select 语句的结果之前，通过薪水选项过滤它。请参阅下面的代码，在此先感谢。

此外，执行时间非常长。 6 分钟以上，对于只有 70 或 80 条记录的 table。我编写查询的方式可能有问题吗？谢谢

select 

a.TicketNo,
a1.Details_PCredit as Salary_Amount_1,
a1.Details_PTransactionDate as Salary_Date_1,
a2.Details_PCredit as Salary_Amount_2,
a2.Details_PTransactionDate as Salary_Date_2,
a3.Details_PCredit as Salary_Amount_3,
a3.Details_PTransactionDate as Salary_Date_3,
a4.Details_PCredit as Salary_Amount_4,
a4.Details_PTransactionDate as Salary_Date_4,
a5.Details_PCredit as Salary_Amount_5,
a5.Details_PTransactionDate as Salary_Date_5,
a6.Details_PCredit as Salary_Amount_6,
a6.Details_PTransactionDate as Salary_Date_6

from staging.MBS_Transactions as a


left join (
select TicketNo, Details_PNarration,
       max(Details_PTransactionDate) as maxDate        
       from staging.MBS_Transactions group by TicketNo
) as a0 on a0.TicketNo=a.TicketNo 
left join staging.MBS_Transactions as a1 on a1.TicketNo=a.TicketNo and a1.Details_PTransactionDate=a0.maxDate 
left join staging.MBS_Transactions as a2 on a2.TicketNo=a1.TicketNo and a2.Details_PTransactionDate<a1.Details_PTransactionDate
left join staging.MBS_Transactions as a3 on a3.TicketNo=a2.TicketNo and a3.Details_PTransactionDate<a2.Details_PTransactionDate
left join staging.MBS_Transactions as a4 on a4.TicketNo=a3.TicketNo and a4.Details_PTransactionDate<a3.Details_PTransactionDate
left join staging.MBS_Transactions as a5 on a5.TicketNo=a4.TicketNo and a5.Details_PTransactionDate<a4.Details_PTransactionDate
left join staging.MBS_Transactions as a6 on a6.TicketNo=a5.TicketNo and a6.Details_PTransactionDate<a5.Details_PTransactionDate
    where  
        (a.Details_PNarration like '%SALARY%' 
        OR a.Details_PNarration like '%Mid MTH%'
        OR a.Details_PNarration like '%Mid Month%'
        OR a.Details_PNarration like '%Mid Month%'
        OR a.Details_PNarration like '%Staff%'
        OR a.Details_PNarration like '%SAL%'
        AND DAY(a.Details_PTransactionDate) between '23' and '25' 
        and WEEKDAY(a.Details_PTransactionDate) Between 0 and 4)

group by a.TicketNo;

Answer 1

您可以在 where

中使用嵌套查询

select 

a.TicketNo,
a1.Details_PCredit as Salary_Amount_1,
a1.Details_PTransactionDate as Salary_Date_1,
a2.Details_PCredit as Salary_Amount_2,
a2.Details_PTransactionDate as Salary_Date_2,
a3.Details_PCredit as Salary_Amount_3,
a3.Details_PTransactionDate as Salary_Date_3,
a4.Details_PCredit as Salary_Amount_4,
a4.Details_PTransactionDate as Salary_Date_4,
a5.Details_PCredit as Salary_Amount_5,
a5.Details_PTransactionDate as Salary_Date_5,
a6.Details_PCredit as Salary_Amount_6,
a6.Details_PTransactionDate as Salary_Date_6

from (SELECT * FROM staging.MBS_Transactions a where  
        (a.Details_PNarration like '%SALARY%' 
        OR a.Details_PNarration like '%Mid MTH%'
        OR a.Details_PNarration like '%Mid Month%'
        OR a.Details_PNarration like '%Mid Month%'
        OR a.Details_PNarration like '%Staff%'
        OR a.Details_PNarration like '%SAL%'
        AND DAY(a.Details_PTransactionDate) between '23' and '25' 
        and WEEKDAY(a.Details_PTransactionDate) Between 0 and 4)) as a


left join (
select TicketNo, Details_PNarration,
       max(Details_PTransactionDate) as maxDate        
       from staging.MBS_Transactions group by TicketNo
) as a0 on a0.TicketNo=a.TicketNo 
left join staging.MBS_Transactions as a1 on a1.TicketNo=a.TicketNo and a1.Details_PTransactionDate=a0.maxDate 
left join staging.MBS_Transactions as a2 on a2.TicketNo=a1.TicketNo and a2.Details_PTransactionDate<a1.Details_PTransactionDate
left join staging.MBS_Transactions as a3 on a3.TicketNo=a2.TicketNo and a3.Details_PTransactionDate<a2.Details_PTransactionDate
left join staging.MBS_Transactions as a4 on a4.TicketNo=a3.TicketNo and a4.Details_PTransactionDate<a3.Details_PTransactionDate
left join staging.MBS_Transactions as a5 on a5.TicketNo=a4.TicketNo and a5.Details_PTransactionDate<a4.Details_PTransactionDate
left join staging.MBS_Transactions as a6 on a6.TicketNo=a5.TicketNo and a6.Details_PTransactionDate<a5.Details_PTransactionDate


group by a.TicketNo;

在 select 语句中的 LEFT JOIN 之前使用 WHERE 子句

use WHERE clause before LEFT JOIN in a select statement

mysql

sql

select

left-join

where-clause