聚合(待续)
array_agg:
聚合函数,返回一个array,相当于oracle的wm_concat:
digoal=# select array_agg(fooid) from foo; array_agg ----------------- {4,5,7,6,1,7,8} (1 row)
setof转换为array:digoal=# select array(select fooid from foo); array ----------------- {4,5,7,6,1,7,8} (1 row)