mysql兩條sql合並查詢總數

select IFNULL(c.nodeCount,0) + IFNULL(c.phyCount,0) as totalCount
 from (
select count(*) nodeCount, (select count(*) from rn_base a join rn_ext_systeminfo b
            on a.id = b.nodeId where (a.subType = 'VIRTUAL' or a.subType = 'PHYSICAL')) phyCount  from rn_base a join rn_ext_vir_instance b 
            on a.id = b.nodeId where a.subType = 'VIR_INSTANCE' ) c