oracle统计无记录时，写默认值
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select ?nvl(max(t1.packagesize),0) ?
from (
? ? ? ? select decode(count(t.per_bus_code),0,'1') per_bus_code,decode(count(t.buss_code),0,'1') buss_code,decode(count(t.per_code),0,'1') per_code?
? ? ? ? ? ?from t_tybook_back_pers_business t
? ? ? ? ? ?where t.per_code = 'TY-00000106'?
? ? ? ? ? ?and t.end_date > sysdate?
? ? ? ? ? ?and t.start_date<=sysdate ) t
left join t_tybook_before_business t1 on t.buss_code = t1.code?
group by t.per_code;
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