逐行减法

Question

我有两个视图，其中包含以下数据：

查看低限

6
13
19

查看上传

3
9
14

我想使用上面两个视图生成此结果

3
4
5

，其中6-3 = 3,13-9 = 4和19-14 = 15。

我试过

 Select l.val - u.val from lowbound l, upbound u;

但这是结果

3
10
16
-3
4
10
-8
-1
5

Answer 1

所以看起来你需要加入view1中最低的数字和view2中最低的数字，依此类推。如果您的DBMS支持ROW_NUMBER，您可以使用类似

的内容

WITH T1
     AS (SELECT V1.val,
                ROW_NUMBER() OVER (ORDER BY val) AS RN
         FROM   View1 V1),
     T2
     AS (SELECT V2.val,
                ROW_NUMBER() OVER (ORDER BY val) AS RN
         FROM   View2 V2)
SELECT T1.val - T2.val
FROM   T1
       JOIN T2
         ON T1.RN = T2.RN

SQL Fiddle

Answer 2

您需要一个存储过程，然后我正在使用MSSQL服务器

 BEGIN
 DECLARE lcursor CURSOR
 FOR SELECT * FROM l;
 DECLARE ucursor CURSOR
 FOR SELECT * FROM u;
 DECLARE @l INT;
 DECLARE @u INT;

 FETCH NEXT FROM lcursor 
 INTO @l
 FETCH NEXT FROM ucursor 
 INTO @u

 WHILE @@FETCH_STATUS = 0
 BEGIN
      PRINT @l - @u
      FETCH NEXT FROM lcursor 
      INTO @l
      FETCH NEXT FROM ucursor 
      INTO @u
END
CLOSE lcursor 
DEALLOCATE lcursor 
CLOSE ucursor 
DEALLOCATE ucursor 
END