Sql 如果可能,最小值/最大值为空的布尔表达式?
是否可以将带有max或min的布尔表达式放入nullif()语句中 比如说Sql 如果可能,最小值/最大值为空的布尔表达式?,sql,tsql,sql-server-2005,boolean,Sql,Tsql,Sql Server 2005,Boolean,是否可以将带有max或min的布尔表达式放入nullif()语句中 比如说 select min(a) as b ---grabbing first value ,max(a) as c --- grabbing last value but could be same as min value, this is the problem ,nullif(min(a), (min(a) = max(a))) ---my idea for a solution that
select
min(a) as b ---grabbing first value
,max(a) as c --- grabbing last value but could be same as min value, this is the problem
,nullif(min(a), (min(a) = max(a))) ---my idea for a solution that didnt work
from table
当字段的值仅出现1次时,尝试删除重复行。我想可能有一种方法可以做到这一点,即先计数,然后剔除所有值超过1的值,但我不确定如何做到这一点。在SQLServer2005上工作,如果可能的话,在t-sql中需要这个,但是在服务器上工作的任何东西都可以
编辑以提供更多信息:
我正在查看订单管理系统中订单的状态历史记录,该系统在每次请求更正时都会使用id进行标记。id是唯一的数字。在该格式1234中,每个orderid都是唯一的,并且在该格式1111111中也是数字的。a代表唯一的修正id。我想看一下顺序,如果一个修正id已经发生了,理想情况下会抓住下一个,如果可能的话会抓住下一个。至少我想要最大值和最小值。我不能只做两列,因为这会将最小值计算两次(使用我的示例),并且不会给出准确的数据
我试图简单地介绍我的示例,但它没有提供足够的信息,以下是更多信息:
SELECT Cast(oi.orderid AS VARCHAR(MAX)) + '.'
+ Cast(oi.orderitemid AS VARCHAR(MAX)) AS OrderNumber,
Min(oici.orderitemcorrectionid) AS a,
Max(oici.orderitemcorrectionid) AS b
FROM Orderitems oi
LEFT JOIN orderitemcorrections oic
ON oic.orderid = oi.orderid
AND oic.orderitemid = oi.orderitemid
LEFT JOIN orderitemcorrectionissues oici
ON oici.orderitemcorrectionid = oic.orderitemcorrectionid
LEFT JOIN correctiontypes ct
ON ct.correctiontypeid = oici.correctiontypeid
GROUP BY Cast(oi.orderid AS VARCHAR(MAX)) + '.'
+ Cast(oi.orderitemid AS VARCHAR(MAX))
上述查询的样本表数据:
OrderNumber a b
1098048.1 1 2
1098210.1 160 160
1098222.1 78 78
1098300.1 31 31
1098408.1 4 4
1098462.1 224 224
1098468.1 602 602
1098492.2 1457 1457
以上是a和b相同的数据
下面是它们的不同之处,但我希望将从a到b的任何重复项都设为空
1100268.1 181 191
1100256.1 306 379
更多数据,未分组以显示行的重复数据。-原始数据样本
OrderNumber orderitemcorrectionid
1098048.1 1
1098048.1 2
1098210.1 160
1098210.1 160
可以通过使用UNION来实现空值化,UNION将删除重复的行。我会这样做
;with tmp AS (
select
CAST(oi.orderid as VARCHAR(MAX))+'.'+CAST(oi.orderitemid as VARCHAR(MAX)) as OrderNumber
,min(oici.orderitemcorrectionid) as a
,max(oici.orderitemcorrectionid) as b
FROM
Orderitems oi
left join orderitemcorrections oic on oic.orderid = oi.orderid and oic.orderitemid = oi.orderitemid
left join orderitemcorrectionissues oici on oici.orderitemcorrectionid = oic.orderitemcorrectionid
left join correctiontypes ct on ct.correctiontypeid = oici.correctiontypeid
GROUP BY
CAST(oi.orderid as VARCHAR(MAX))+'.'+CAST(oi.orderitemid as VARCHAR(MAX))
)
select OrderNumber, a
from tmp
union
select OrderNumber, b
from tmp
这将a和b放在不同的行中,Union负责删除重复项。可能类似于:
SELECT Cast(oi.orderid AS VARCHAR(MAX)) + '.'
+ Cast(oi.orderitemid AS VARCHAR(MAX)) AS OrderNumber,
COALESCE(Min(oici.orderitemcorrectionid),Max(oici.orderitemcorrectionid),0) AS a,
COALESCE(Max(oici.orderitemcorrectionid),Min(oici.orderitemcorrectionid),0) AS b
FROM Orderitems oi
LEFT JOIN orderitemcorrections oic
ON oic.orderid = oi.orderid
AND oic.orderitemid = oi.orderitemid
LEFT JOIN orderitemcorrectionissues oici
ON oici.orderitemcorrectionid = oic.orderitemcorrectionid
LEFT JOIN correctiontypes ct
ON ct.correctiontypeid = oici.correctiontypeid
GROUP BY Cast(oi.orderid AS VARCHAR(MAX)) + '.'
+ Cast(oi.orderitemid AS VARCHAR(MAX))
不过,我可能无法理解,所以请善待我。你最好解释一下你的根本问题。如果是如何识别重复项,那么请提供一些示例架构/数据。好的,很抱歉缺少信息,我认为这更像是一个语法问题。如果你要提供大约10行虚拟数据并给出该数据的示例结果,我会亲自编辑我的帖子,这可能会让事情变得更清楚。因此,你的最终表(不分组)是原始数据的样子,你想要的结果与你标题为“示例表数据”的表类似除了如果
a=b
之外,b的值应该为空?要修改原始查询,您只需要当Min(oici.orderitemcorrectionid)Max(oici.orderitemcorrectionid)然后Max(oici.orderitemcorrectionid)时的情况结束为b
在所有这些之后,但看起来您现在有了一些其他选择。这帮助我更接近我所需要的,我在这个查询中有其他问题来获得我所需要的,但这让我克服了一个障碍,谢谢。