如何使用MDX编写同比和环比
在做BI项目中，用户会经常提出类似下面这样的需求：
1. 本月比上月的销售额增长了多少？百分比是多少？
2. 本季度第一个月比上季度第一个月的销售额增长了多少？百分比是多少？
其实这两个需求就是我们常说的同比和环比问题，它们用关系数据库的SQL语句难于实现，而用BI中的MDX来做却轻而易举。以下例子采用的是SQL Server2005的Analysis Services中的示例库。
环比
需求：本月比上个月的销售额增长了多少个百分点？
MDX语句如下：
WITH
MEMBER Measures.
[
Amount Change Rate
]
AS
[
Measures
]
.
[
Internet Sales Amount
]
/
(
[
Measures
]
.
[
Internet Sales Amount
]
,
[
Date
]
.
[
Fiscal
]
.CurrentMember.PrevMember)
-
1
, FORMAT_STRING
=
'
0%
'
SELECT
{
[
Measures
]
.
[
Internet Sales Amount
]
, Measures.
[
Amount Change Rate
]
}
ON
0
,
[
Date
]
.
[
Fiscal
]
.
[
Month
]
.Members
ON
1
FROM
[
Adventure Works
]
结果如下：
上面的输出结果有一个问题，就是第一行数据会发生除0的情况，为了防止这种情况，MDX修改如下：
WITH
MEMBER Measures.
[
Amount Change Rate
]
AS
IIF(ISEMPTY((
[
Measures
]
.
[
Internet Sales Amount
]
,
[
Date
]
.
[
Fiscal
]
.CurrentMember.PrevMember)), "",
[
Measures
]
.
[
Internet Sales Amount
]
/
(
[
Measures
]
.
[
Internet Sales Amount
]
,
[
Date
]
.
[
Fiscal
]
.CurrentMember.PrevMember)
-
1
), FORMAT_STRING
=
'
0%
'
SELECT
{
[
Measures
]
.
[
Internet Sales Amount
]
, Measures.
[
Amount Change Rate
]
}
ON
0
,
[
Date
]
.
[
Fiscal
]
.
[
Month
]
.Members
ON
1
FROM
[
Adventure Works
]
如果发现0为空，则显示空字符串。输出结果如下：
同比
需求：本季度每个月比上个季度同期销售额增长了多少个百分点？
WITH
MEMBER Measures.
[
Change Amount Rate
]
AS
[
Measures
]
.
[
Internet Sales Amount
]
/
(
[
Measures
]
.
[
Internet Sales Amount
]
,
Cousin(
[
Date
]
.
[
Fiscal
]
.CurrentMember,
[
Date
]
.
[
Fiscal
]
.CurrentMember.Parent.PrevMember)
)
-
1
, FORMAT_STRING
=
'
0%
'
SELECT
{
[
Measures
]
.
[
Internet Sales Amount
]
, Measures.
[
Change Amount Rate
]
}
ON
0
,
[
Date
]
.
[
Fiscal
]
.
[
Month
]
.Members
ON
1
FROM
[
Adventure Works
]
运行结果如下：
和环比相同，这里也出现了除0的情况，所以把MDX做如下修改：
WITH
MEMBER Measures.
[
Change Amount Rate
]
AS
IIF(
(
[
Measures
]
.
[
Internet Sales Amount
]
,
Cousin(
[
Date
]
.
[
Fiscal
]
.CurrentMember,
[
Date
]
.
[
Fiscal
]
.CurrentMember.Parent.PrevMember)
)=0
, "",
[
Measures
]
.
[
Internet Sales Amount
]
/
(
[
Measures
]
.
[
Internet Sales Amount
]
,
Cousin(
[
Date
]
.
[
Fiscal
]
.CurrentMember,
[
Date
]
.
[
Fiscal
]
.CurrentMember.Parent.PrevMember)
)
-
1
), FORMAT_STRING
=
'
0%
'
SELECT
{
[
Measures
]
.
[
Internet Sales Amount
]
, Measures.
[
Change Amount Rate
]
}
ON
0
,
[
Date
]
.
[
Fiscal
]
.
[
Month
]
.Members
ON
1
FROM
[
Adventure Works
]
输出结果如下：
总结
同比和环比是BI项目中经常要做得内容，采用MDX语句可以轻松的实现这个需求。
1. 本月比上月的销售额增长了多少？百分比是多少？
2. 本季度第一个月比上季度第一个月的销售额增长了多少？百分比是多少？
其实这两个需求就是我们常说的同比和环比问题，它们用关系数据库的SQL语句难于实现，而用BI中的MDX来做却轻而易举。以下例子采用的是SQL Server2005的Analysis Services中的示例库。
环比
需求：本月比上个月的销售额增长了多少个百分点？
MDX语句如下：
WITH
MEMBER Measures.
[
Amount Change Rate
]
AS
[
Measures
]
.
[
Internet Sales Amount
]
/
(
[
Measures
]
.
[
Internet Sales Amount
]
,
[
Date
]
.
[
Fiscal
]
.CurrentMember.PrevMember)
-
1
, FORMAT_STRING
=
'
0%
'
SELECT
{
[
Measures
]
.
[
Internet Sales Amount
]
, Measures.
[
Amount Change Rate
]
}
ON
0
,
[
Date
]
.
[
Fiscal
]
.
[
Month
]
.Members
ON
1
FROM
[
Adventure Works
]
结果如下：
上面的输出结果有一个问题，就是第一行数据会发生除0的情况，为了防止这种情况，MDX修改如下：
WITH
MEMBER Measures.
[
Amount Change Rate
]
AS
IIF(ISEMPTY((
[
Measures
]
.
[
Internet Sales Amount
]
,
[
Date
]
.
[
Fiscal
]
.CurrentMember.PrevMember)), "",
[
Measures
]
.
[
Internet Sales Amount
]
/
(
[
Measures
]
.
[
Internet Sales Amount
]
,
[
Date
]
.
[
Fiscal
]
.CurrentMember.PrevMember)
-
1
), FORMAT_STRING
=
'
0%
'
SELECT
{
[
Measures
]
.
[
Internet Sales Amount
]
, Measures.
[
Amount Change Rate
]
}
ON
0
,
[
Date
]
.
[
Fiscal
]
.
[
Month
]
.Members
ON
1
FROM
[
Adventure Works
]
如果发现0为空，则显示空字符串。输出结果如下：
同比
需求：本季度每个月比上个季度同期销售额增长了多少个百分点？
WITH
MEMBER Measures.
[
Change Amount Rate
]
AS
[
Measures
]
.
[
Internet Sales Amount
]
/
(
[
Measures
]
.
[
Internet Sales Amount
]
, Cousin(
[
Date
]
.
[
Fiscal
]
.CurrentMember,
[
Date
]
.
[
Fiscal
]
.CurrentMember.Parent.PrevMember) )
-
1
, FORMAT_STRING
=
'
0%
'
SELECT
{
[
Measures
]
.
[
Internet Sales Amount
]
, Measures.
[
Change Amount Rate
]
}
ON
0
,
[
Date
]
.
[
Fiscal
]
.
[
Month
]
.Members
ON
1
FROM
[
Adventure Works
]
运行结果如下：
和环比相同，这里也出现了除0的情况，所以把MDX做如下修改：
WITH
MEMBER Measures.
[
Change Amount Rate
]
AS
IIF( (
[
Measures
]
.
[
Internet Sales Amount
]
, Cousin(
[
Date
]
.
[
Fiscal
]
.CurrentMember,
[
Date
]
.
[
Fiscal
]
.CurrentMember.Parent.PrevMember) )=0 , "",
[
Measures
]
.
[
Internet Sales Amount
]
/
(
[
Measures
]
.
[
Internet Sales Amount
]
, Cousin(
[
Date
]
.
[
Fiscal
]
.CurrentMember,
[
Date
]
.
[
Fiscal
]
.CurrentMember.Parent.PrevMember) )
-
1
), FORMAT_STRING
=
'
0%
'
SELECT
{
[
Measures
]
.
[
Internet Sales Amount
]
, Measures.
[
Change Amount Rate
]
}
ON
0
,
[
Date
]
.
[
Fiscal
]
.
[
Month
]
.Members
ON
1
FROM
[
Adventure Works
]
输出结果如下：
总结
同比和环比是BI项目中经常要做得内容，采用MDX语句可以轻松的实现这个需求。