我将客户余额存储在自己的表中。客户余额表每天获取一组新记录（反映当天的余额），但包含其他日期的余额（yyyy-mm-dd）。我想从accountinformation获取balances的所有英国客户及其余额accountinformation。我希望包含来自balances的行，即使select firstname,lastname,accountnumber,balance from accountinformation i
left outer join balances b
on i.accountnumber = b.account
where country = 'UK' and status = 'OPEN'
and (b.date = '2014-04-10' or b.date is null)
中没有相应的记录（昨天）......
accountinformation ...如果balances中没有相应的行，则不满足显示select firstname,lastname,accountnumber,balance from accountinformation i
left outer join (select * from balances where date = '2014-04-10') b
on i.accountnumber = b.account
where country = 'UK' and status = 'OPEN'
行的要求。我不得不写这样的查询...
left outer..以获得理想的行为。为了正确起见，我想知道是否有更正确的方法来过滤{{1}}联接中的左表？
答案 0 :(得分：2)
你可以做到
select firstname,lastname,accountnumber,balance from accountinformation i
left outer join balances b
on i.accountnumber = b.account and b.date = '2014-04-10'
where country = 'UK' and status = 'OPEN'