一个时间条件查询语句问怎么写！！急
语句如是：
SELECT   UNIT_ID,SUM(BOROUGH_ADVICEASSISNUM)ADVICEASSISNUM,count(EXTEND_ID)EXTEND_ID,SUM(BOROUGH_ADVICESUBSIDY)ADVICESUBSIDY
FROM   T_BYW_JZFF  
WHERE   SALVATION_YEAR_MON=@SALVATION_YEARMON   AND   REVIEW_UNIT_ID= "1 "  
GROUP   BY   REVIEW_UNIT_ID

SALVATION_YEAR_MON   是时间字段为字符型

怎么样取到时间为当前系统时间的年月并做为条件进行查询
运行语句列SALVATION_YEAR_MON=200709

------解决方案--------------------
select convert(varchar(6),getdate(),112)
------解决方案--------------------
存储过程中经常用到的本周，本月，本年函数
Dateadd(wk,datediff(wk,0,getdate()),-1)
Dateadd(wk,datediff(wk,0,getdate()),6)
Dateadd(mm,datediff(mm,0,getdate()),0)
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0))

Dateadd(yy,datediff(yy,0,getdate()),0)
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0))