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分享怎么该写成 relational algebra ??
select contactname
from client
where companyname in (
select clientname from campaign
where startdate = to_date('02-sep-2002', 'dd-mon-yyyy')
and finishdate = to_date('04-apr-2004', 'dd-mon-yyyy'));
这个
怎么该写成 relational algebra ??
关键是那个in
from client
where companyname in (
select clientname from campaign
where startdate = to_date('02-sep-2002', 'dd-mon-yyyy')
and finishdate = to_date('04-apr-2004', 'dd-mon-yyyy'));
这个
怎么该写成 relational algebra ??
关键是那个in
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zmgowin 2004-10-08
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select a.contactname
from client a,campaign b
where a.companyname=b.clientname and
b.startdate = to_date('02-sep-2002', 'dd-mon-yyyy') and
b.finishdate = to_date('04-apr-2004', 'dd-mon-yyyy'));
from client a,campaign b
where a.companyname=b.clientname and
b.startdate = to_date('02-sep-2002', 'dd-mon-yyyy') and
b.finishdate = to_date('04-apr-2004', 'dd-mon-yyyy'));
