带 SUM 的 CASE 语句

Question

这是我的 table 结构。

===================================
main_section | currency | amount
===================================

Tender           INR        2000
Bank             USD        3000
Tender           INR        1500
Tender           INR        1850
===================================

我正在尝试做一个 CASE 语句，其中如果 'main_section=tender' 它应该 return 投标金额，如果它的银行它应该 return 银行金额。如果有不止一条记录，那么它应该求和 return 金额（这里 Tender 有不止一条记录）。谁能帮我这个。以下是我试过的案例陈述

CASE sum(com_payments.main_section 
         WHEN com_payments.main_section = 'Tender' 
         THEN main_tender = com_payments.amount
END AS maintender1)
CASE sum(com_payments.main_section 
         WHEN com_payments.main_section = 'Bank' 
         THEN main_bank = com_payments.amount
END AS mainbank1)

Answer 1

你必须做条件聚合:

SELECT SUM(CASE WHEN main_section = 'Tender' THEN amount END) AS maintender1,
       SUM(CASE WHEN main_section = 'Bank' THEN amount END) AS mainbank1      
FROM mytable

带 SUM 的 CASE 语句

CASE Statement with a SUM

mysql

case

case-statement