使用 PostgreSQL 合并表

宇很可能是在寻找对FULL OUTER JOIN

SELECt  coalesce(a.pre,b.pre),  coalesce(a."year",b.year),  coalesce(a.nb_a,0),  coalesce(b.nb_b,0),  coalesce(a.nb_a,0) + coalesce(b.nb_b,0) AS totalFROM table_a a full outer join table_b b on a.pre = b.pre and a.year = b.year; coalesce | coalesce | coalesce | coalesce | total----------+----------+----------+----------+-------        1 |     2013 |        0 |        1 |     1        1 |     2014 |        0 |        1 |     1        1 |     2017 |        1 |        0 |     1        2 |     2012 |        2 |        1 |     3        3 |     2014 |        2 |        0 |     2(5 rows)