我有两个存储电子邮件信息的表:
EMAIL有:
EMAIL_ADDRESS具有:
假设我在EMAIL中有6行-查询应返回ID,时间戳记以及往返地址。
目前,我有这个:
SELECT ea.EMAIL_ADDRESS, e.ID, e.sent_date
FROM EMAIL_ADDRESS ea, CHANN_EMAIL e
WHERE e.ID=ea.id
AND ea.TYPE in ('to','from')
这将返回12行,其格式为:-to,ID,日期-from,ID,日期
该查询将是什么,所以我将有6行:-to,from,ID,日期
您必须将EMAIL_ADDRESS表与两个视图区分开:
SELECT eat.EMAIL_ADDRESS as to ,ea.EMAIL_ADDRESS as from, e.ID, e.sent_date
FROM EMAIL_ADDRESS ea, CHANN_EMAIL e,EMAIL_ADDRESS eat
WHERE e.ID=ea.id and e.ID=eat.id
AND ea.TYPE in ('from') AND eat.TYPE in ('to')
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