SELECT to_char(to_timestamp(bigInt_time / 1000), 'YYYY-MM-DD HH24:MI:SS')
2、将long类型ip转化文string 类型
select ip2str(ip_address) from test;
3、case.....when 的用法
select (case when cc.urlgrp_name is not null then cc.urlgrp_name else '其他类网站' end) urlgrp_name
4、postgresql 多行拼接成一行关键字:string_agg(字段名,',')------按照逗号拼接改字段的值。array_agg(字段名),array_to_string(array_agg(tag),','),array_agg(distinct(字段名)) 拼接唯一的字段
id | name | tag
----+------+-----
1 | java | aa
1 | java | bb
1 | java | cc
2 | C++ | dd
2 | C++ | ee
1)
postgres=# select name,string_agg(tag,',') from book2 group by name;
name | string_agg
------+------------
C++ | dd,ee
java | aa,bb,cc
2)
postgres=# select name,array_agg(tag) from tb3 group by name;
name | array_agg
------+------------
c++ | {dd,ee}
java | {aa,bb,cc}
postgres=# select name,array_to_string(array_agg(tag),',') from tb3 group by name;
name | array_to_string
------+-----------------
c++ | dd,ee
java | aa,bb,cc