改为：SELECT count(*) as num FROM (income as i join outgo as o on i.areaid=o.areaid) join centeroutgo as c on i.areaid =c.areaid 还有就是确保income表、outgo表和centeroutgo表这三个表的areaid字段类型一致。我没见过有Full outer join的，查了下手册，也没看见。join_...
mysql 三个表怎么全连接查询
改为：
SELECT count(*) as num FROM (income as i join outgo as o on i.areaid=o.areaid) join centeroutgo as c on i.areaid =c.areaid
还有就是确保income表、outgo表和centeroutgo表这三个表的areaid字段类型一致。
我没见过有Full outer join的，查了下手册，也没看见。
join_table:
table_reference [INNER | CROSS] JOIN table_factor [join_condition]
| table_reference STRAIGHT_JOIN table_factor
| table_reference STRAIGHT_JOIN table_factor ON condition
| table_reference LEFT [OUTER] JOIN table_reference join_condition
| table_reference NATURAL [LEFT [OUTER]] JOIN table_factor
| table_reference RIGHT [OUTER] JOIN table_reference join_condition
| table_reference NATURAL [RIGHT [OUTER]] JOIN table_factor2010-12-21
