总价格，折旧值查出来了，我怎样同时增加已折旧率

[wufayou2015]

select _type as 部门,sum(_oldPrice) as 总价值,sum(_zzjz) as 已折旧值,sum(_jcz) as 净残值 from IT_zj group by _type

上面语句总价格，折旧值查出来了，我怎样同时增加已折旧率，就是已折旧值除以总价格，怎么写这个语句？

[听雨停了]

SELECT _type           AS 部门,
       SUM(_oldPrice)  AS 总价值,
       SUM(_zzjz)      AS 已折旧值,
       SUM(_jcz)       AS 净残值,
       CAST(CAST(SUM(_zzjz)/SUM(_oldPrice) as decimal(18,2)) AS VARCHAR(200))+'%' AS 已折旧率
FROM   IT_zj
GROUP BY _type

[二月十六]

SELECT  _type AS 部门 ,
        SUM(_oldPrice) AS 总价值 ,
        SUM(_zzjz) AS 已折旧值 ,
        SUM(_jcz) AS 净残值 ,
        SUM(_zzjz) / SUM(_oldPrice) AS 已折旧率
FROM    IT_zj
GROUP BY _type