本文介绍了根据不同的值从列中选择随机值的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我在表中有以下数据:-
I have following data in table :-
| item | rate |
-------------------
| a | 50 |
| a | 12 |
| a | 26 |
| b | 12 |
| b | 15 |
| b | 45 |
| b | 10 |
| c | 5 |
| c | 15 |
我需要一个返回以下输出的查询:
and i need a query which return following output :
| item no | rate |
------------------
| a | 12 | --from (26 , 12 , 50)
| b | 45 | --from (12 ,15 , 45 , 10)
| c | 5 | --from (5 , 15)
即 item_no 应该是不同的并且具有随机一个速率值..
i.e item_no should be distinct and with randomly one rate value..
提前致谢
推荐答案
WITH
CTE
AS
(
SELECT DISTINCT
item
FROM T
)
SELECT
CTE.item
,A.rate
FROM
CTE
CROSS APPLY
(
SELECT TOP(1)
T.rate
FROM T
WHERE T.item = CTE.item
ORDER BY CRYPT_GEN_RANDOM(4)
) AS A
;
(item) include (rate)
上的索引会有所帮助.
Index on (item) include (rate)
would help.
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