Question

我有一个oracle sql，我在accounts表和payment表之间进行外连接。我想知道如何在付款表中有匹配的记录时执行条件p.payment_status_code ='R'。其余的，不应该执行条件。

FROM
accounts a, payments p
WHERE (a.account_balance <= a.low_balance_level OR a.account_balance <= 0)
AND a.account_id = p.account_id(+)
AND p.payment_status_code = 'R'

此致 -Anand

Answer 1

FROM
accounts a, payments p
WHERE (a.account_balance <= a.low_balance_level OR a.account_balance <= 0)
AND a.account_id = p.account_id(+)

AND p.payment_status_code(+) = 'R'
                         ^^^

Answer 2

如果我理解正确，您只想用payment_status_code = 'R'显示结果，对吧？在那种情况下，为什么你需要使用外连接？你可以使用传统的连接。你想做什么？

FROM
accounts a, payments p
WHERE (a.account_balance <= a.low_balance_level OR a.account_balance <= 0)
AND a.account_id = p.account_id
AND p.payment_status_code = 'R'

如果您想显示帐户信息，即使是没有付款的用户，也可以使用左外连接而不是右外连接

FROM
accounts a
left join payments p on a.account_id = p.account_id AND p.payment_status_code = 'R'
WHERE (a.account_balance <= a.low_balance_level OR a.account_balance <= 0)

Answer 3

FROM
accounts a, payments p
WHERE (a.account_balance <= a.low_balance_level OR a.account_balance <= 0)
AND a.account_id = p.account_id(+)
AND (p.account_id is null or p.payment_status_code = 'R')

Oracle右外连接

3 个答案: