我希望使用mysql在使用多个条件的单个查询中使用sum和substarct函数创建查询

在上表中，我想求和其中的

ledgertype='Earning'

，并在其中减去

ledgertype='reduction'

并显示这两个值。。。。。如何编写查询

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提前感谢…

您可以使用此功能实现。因为您还想打印收入和扣除额，所以我使用了子查询

select sum_earnings , sum_deduction , sum_earnings - sum_deduction 
from ( select sum(case when ledgertype = 'Earning' then ledgervalue end) sum_earrnings,  sum(case when ledgertype = 'Deductions' then ledgervalue end) as sum(sum_deduction) 
from ratecard ) a

我无法理解“两种值”，但您可以通过以下方式获得两种类型的聚合：

Select SUM(ledgerValue), ledgerType FROM ratecard group by ledgerType

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如果您想要一个运行总数，您可以使用一个变量来计算

DROP TABLE IF EXISTS T;
CREATE TABLE T (ID INT,AMOUNT INT, TYP VARCHAR(10));
INSERT INTO T VALUES
(1,12500,'Earnings'),(2,3200,'Earnings'),(3,1200,'Earnings'),
(4,1200,'Deductions'),(5,200,'Deductions'),(6,600,'Deductions'),(7,500,'Deductions'),
(8,12000,'Earnings'),(9,3200,'Deductions');


select t.*,
         if(t.`typ` = 'Earnings' ,@rt:=@rt+amount,@rt:=@rt-amount) RunningTotal
from t
,(select @rt:=0) rt;
order by t.id

+------+--------+------------+--------------+
| ID   | AMOUNT | TYP        | RunningTotal |
+------+--------+------------+--------------+
|    1 |  12500 | Earnings   |        12500 |
|    2 |   3200 | Earnings   |        15700 |
|    3 |   1200 | Earnings   |        16900 |
|    4 |   1200 | Deductions |        15700 |
|    5 |    200 | Deductions |        15500 |
|    6 |    600 | Deductions |        14900 |
|    7 |    500 | Deductions |        14400 |
|    8 |  12000 | Earnings   |        26400 |
|    9 |   3200 | Deductions |        23200 |
+------+--------+------------+--------------+
9 rows in set (0.00 sec)

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你在追求一个总价值吗？所有收入-所有扣除额？请参阅，虽然此代码可以回答问题，但提供有关如何和/或为什么解决问题的其他上下文将提高答案的长期价值。基于此url获取查询并删除此查询中的限制

DROP TABLE IF EXISTS T;
CREATE TABLE T (ID INT,AMOUNT INT, TYP VARCHAR(10));
INSERT INTO T VALUES
(1,12500,'Earnings'),(2,3200,'Earnings'),(3,1200,'Earnings'),
(4,1200,'Deductions'),(5,200,'Deductions'),(6,600,'Deductions'),(7,500,'Deductions'),
(8,12000,'Earnings'),(9,3200,'Deductions');


select t.*,
         if(t.`typ` = 'Earnings' ,@rt:=@rt+amount,@rt:=@rt-amount) RunningTotal
from t
,(select @rt:=0) rt;
order by t.id

+------+--------+------------+--------------+
| ID   | AMOUNT | TYP        | RunningTotal |
+------+--------+------------+--------------+
|    1 |  12500 | Earnings   |        12500 |
|    2 |   3200 | Earnings   |        15700 |
|    3 |   1200 | Earnings   |        16900 |
|    4 |   1200 | Deductions |        15700 |
|    5 |    200 | Deductions |        15500 |
|    6 |    600 | Deductions |        14900 |
|    7 |    500 | Deductions |        14400 |
|    8 |  12000 | Earnings   |        26400 |
|    9 |   3200 | Deductions |        23200 |
+------+--------+------------+--------------+
9 rows in set (0.00 sec)