你现在是求了数据库的表里面最大年月的数据。那你得到后。。。。最大年月后。还要把它限制为去年的同期。。。不知道你是什么数据库，，我以oracle中来写类似如下

select '日期：'||substr(t1.time,1,4)||'.'||substr(t1.time,5,2) time,

       t1.PROD_CLASS_NAME,

       t1.月实际,

       t2.月预算

from

(select YEAR || MONTH AS TIME,PROD_CLASS_NAME,PROCESSING_COST 月实际

from MAMC00.T_ADS_SRV_JYAC_0004

where YEAR || MONTH =(SELECT MAX(YEAR || MONTH)FROM MAMC00.T_ADS_SRV_JYAC_0004

where 1=1

${if(len(COMPANY_NAME) == 0,"","and COMPANY_NAME = '" + COMPANY_NAME + "'")}

)

${if(len(COMPANY_NAME) == 0,"","and COMPANY_NAME = '" + COMPANY_NAME + "'")}

group by YEAR ||MONTH,PROD_CLASS_NAME,PROCESSING_COST)t1

left join

(

select YEAR || MONTH AS TIME,PROD_CLASS_NAME,PROCESSING_COST 月预算

from MAMC00.T_ADS_SRV_JYAC_0007

where YEAR || MONTH =(SELECT MAX(YEAR || MONTH)FROM MAMC00.T_ADS_SRV_JYAC_0007

where 1=1

${if(len(COMPANY_NAME) == 0,"","and COMPANY_NAME = '" + COMPANY_NAME + "'")}

)

${if(len(COMPANY_NAME) == 0,"","and COMPANY_NAME = '" + COMPANY_NAME + "'")}

group by YEAR ||MONTH,PROD_CLASS_NAME,PROCESSING_COST

) t2 on t1.time=t2.time

/*同期实际的数据*/

left join 

(

select YEAR || MONTH AS TIME,PROD_CLASS_NAME,PROCESSING_COST 月预算

from MAMC00.T_ADS_SRV_JYAC_0007

/*求出最大的年月后减100就是去年同期的了。如果不对，那么就是月份前面的0丢失。要转换*/

/*因为不知道你是什么数据库我没有转换。反正是这个思路。oracle中把数字转换成两位数*/

/*to_char(month,'fm00')*/

where YEAR || MONTH =(SELECT MAX(YEAR || MONTH)-100 FROM MAMC00.T_ADS_SRV_JYAC_0007

where 1=1

${if(len(COMPANY_NAME) == 0,"","and COMPANY_NAME = '" + COMPANY_NAME + "'")}

)

${if(len(COMPANY_NAME) == 0,"","and COMPANY_NAME = '" + COMPANY_NAME + "'")}

group by YEAR ||MONTH,PROD_CLASS_NAME,PROCESSING_COST

) t3 on t1.time=t3.time