Question

可能重复：
Simple update statement so that all rows are assigned a different value

有没有办法从子查询中选择一个随机值（如颜色）？这是我尝试过但在每次运行中得到相同的值：

SELECT TOP (100) ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) AS ID,--Sequential number from 1 to ..
                 (SELECT TOP 1 color
                  FROM   ( VALUES (0, 'Red'),
                                  (1, 'Green'),
                                  (2, 'Yellow') ) colors(id, color)
                  ORDER  BY NEWID() )                        AS RandomColor
FROM   sys.all_columns ac1
       CROSS JOIN sys.all_columns ac2

但如果我单独运行这件作品，我会得到不同的颜色：

SELECT TOP 1 color
FROM   ( VALUES (0, 'Red'),
                (1, 'Green'),
                (2, 'Yellow') ) colors(id, color)
ORDER  BY NEWID()

Answer 1

这样的事可能

select ac1.ID, r.color from
(SELECT TOP (100)
-- changed because it didn't work in mssql 2012
--ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) as ID,
ROW_NUMBER() OVER (ORDER BY newid()) as ID,
ROW_NUMBER() OVER (ORDER BY newid()) as dummy
FROM sys.all_columns
order by id
) ac1
cross apply
(SELECT top 1 color FROM ( VALUES (0,'Red'),(1,'Green'),(2,'Yellow') ) colors(id,color) 
where id = dummy % 3
) r

从集合T-SQL中选择一个随机值

1 个答案: