創建表

CREATE TABLE [dbo].[test](
    [id] [int] IDENTITY(1,1) NOT NULL,
    [RQ] [date] NULL,
    [SR] [int] NULL,
    [ZC] [int] NULL
) ON [PRIMARY]

插入數據

INSERT INTO [demo].[dbo].[test]([id],[RQ],[SR],[ZC])
VALUES(1,‘2017-10-01 00:00:00‘,30,NULL);
INSERT INTO [demo].[dbo].[test]([id],[RQ],[SR],[ZC])
VALUES(2
 
,‘2017-10-02 00:00:00‘,NULL,20);
INSERT INTO [demo].[dbo].[test]([id],[RQ],[SR],[ZC])
VALUES(3,‘2017-10-03 00:00:00‘,20,NULL);
INSERT INTO [demo].[dbo].[test]([id],[RQ],[SR],[ZC])
VALUES(4,‘2017-10-04 00:00:00‘,NULL,10);
INSERT INTO [demo].[dbo].[test]([id],[RQ],[SR],[ZC])
VALUES(5,‘2017-10-06 00:00:00‘,40,NULL);

日期字段不重復

SELECT t.RQ, t.SR, t.ZC, (
           
 
SELECT SUM(SR) -SUM(ZC)
           FROM   test
           WHERE  rq <= t.rq
       )     AS 余額
FROM   test  AS t

日期不唯一， 用自增字段來區分：

SELECT t.ID,t.RQ, t.SR, t.ZC, (
           SELECT SUM(SR) -SUM(ZC)
           FROM   test
           WHERE  ID <= t.id
       )     AS 余額
FROM   test  AS t

效果

SQL 流水賬余額查詢