select a.companyno as companyno,sum(nvl(a.transdays,0)) as amount from RcyhMachtrans a,Company b where a.companyno = b.companyno
nvl(a.transdays,0) 这个函数表示当a.transdays为空时默认值显示为0
select a.companyno as companyno,sum(nvl(a.transdays,0)) as amount from RcyhMachtrans a,Company b where a.companyno = b.companyno
nvl(a.transdays,0) 这个函数表示当a.transdays为空时默认值显示为0
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