Question

我有一个表包括1列ID和12列月（Month01到Month12）。如果我有一个参数@ month = 9，我如何比较获得没有Month10，Month11，Month12的第Month01到Month09列。请帮帮我！

Answer 1

你也可以试试这个：）

DECLARE @month int  = 9
DECLARE @Sql nvarchar(100) =''
DECLARE @pos int = 1
WHILE(@pos <= @month)
BEGIN
   SET @Sql = @Sql + (',month' + right('00'+ rtrim(@pos), 2)) 
   SET @pos = @pos + 1
END
SET @Sql= 'SELECT ID ' +@Sql + ' FROM table'
EXEC sp_executesql @Sql

Answer 2

DECLARE @month int
DECLARE @tableName nvarchar(128)

SET @month = 9;
SET @tableName = 'months' -- YOUR TABLE's NAME

DECLARE @query nvarchar(2048)
SET @query = 
'SELECT id, ' + STUFF((SELECT DISTINCT ', ' + name 
   FROM sys.columns WHERE name LIKE'Month%' 
   AND object_id = OBJECT_ID(@tableName)
   AND CONVERT(INT, RIGHT(name, 2)) <= @month 
   FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'),1,1,'') 
   + ' FROM ' + @tableName;  

EXEC(@query)

Answer 3

Simo的答案更优雅，但下面是另一种选择＆＃34; basic＆＃34;这样做的方法：

DECLARE @month INT SET @month = 9 IF @Month = 1 BEGIN SELECT Id, Month01 FROM MonthlyData END IF @Month = 2 BEGIN SELECT Id, Month01, Month02 FROM MonthlyData END -- Repeat for months 3-9 IF @Month = 9 BEGIN SELECT Id, Month01, Month02, Month03, Month04, Month05, Month06, Month07, Month08, Month09 FROM MonthlyData END -- Repeat for months 10-12

查看我的SQL Fiddle。

Answer 4

declare @str varchar(1000)

SELECT @str= coalesce(@str + ', ', '') + a.name 
FROM (
      Select name from sys.columns
      where object_id = OBJECT_ID('table_months')
      and isnumeric(right(name,2))= 1 and name like 'month%'
      and cast(right(name,2) as int) < '03') a

- 而不是＆＃39; 03＆＃39;您使用变量并指定所需的飞蛾数

declare @sql  nvarchar(100)

set @sql = 'select ID, '+ @str+' from table_months'

exec sp_executesql @sql

我该如何解决这个问题？

4 个答案: