SQL 的 union 的作法

The UNION query allows you to combine the result sets of 2 or more “select” queries. It removes duplicate rows between the various “select” statements. select count(1) from (       — 賣家       select ctrl_rowid       from bidleader.sold_record s       where s.ctrl_date like ‘200701%’       group by ctrl_rowid       union       — 買家       select […]