select 

${type} as 类型,

RegionCnName,

sum(isnull(RealWeight,0))/1000 as weight

from  (

select 

WorkSheetCode,

RegionCnName,

RealWeight,

syear as 年份,

syearmonth AS 月份 ,

SalesCompanyName,

ServiceType

from 

[DW_CAMS].[dbo].[DWD_ORDERS]

where 

ServiceType like '%空运%'

AND RegionCnName IS NOT NULL 

${if(${type} = "年份","and syear between '"+ Y1 +"' and  '"+ Y2 +"' ","and syearmonth between  '" + YM1 + "' and '" + YM2 + "' ")}

) a 

group by 

${type},

RegionCnName

如上述语句  想达到的效果是 当${type} 为 年份时， 则为  and syear between '${Y1}' AND '${Y2}'   当{type} 为 月份时 ，则为 syearmonth between '${YM1}' and '${YM1}'

哪位大神知道怎么写这段语句  ，请不吝赐教！谢谢