大连某公司机试POSTGRESQL题目，个人回来后总结的答案

机试失败了，给的是window 2003server的机器，postgresql 9.3，现在都习惯用ubuntu了自家笔记本都是ubuntu，以后面试不知道怎么办，回来参考postgresql官方文档一小时不到就全解决了，说实在的我真没接触过postgresql的存储过程，要我看着别人的代码模仿写真痛苦，尤其是没一点pgsql的语法基础，废话不说上题目和答案(说的是招聘JAVA结果全面的postgresql汗颜。。。)

环境ubuntu,postgresql 9.3

1.恢复pg_dump的输出文件

psql

create user mianshi superuser login createdb password 'mianshi'

create tablespace mianshi_ts owner mianshi location '/windows/data/pgdata'

create database mianshi owner=mianshi tablespace=mianshi_ts

\q

psql -h localhost -U mianshi

\i mianshi.bak

2.postgresql 递归实现

create table tb_tree(id int,pid int ,name varchar(8000));

insert into tb_tree values(1,null,'祖父'),(2,1,'父亲'),(3,2,'本人'),(4,2,'弟弟');

with RECURSIVE t(id,pid,name) as (select * from tb_tree where name='本人' union all select tb_tree.* from tb_tree,t where tb_tree.id=t.pid) select * from t;

3.计算一个时间的年龄

select age(timestamp '1985-05-15 5:5:5');

4.计算两个时间距离的天数

select current_date - (timestamp '2014-2-27 1:1:1')::date;

5.计算两个时间间隔的秒数

select extract(epoch from current_timestamp - (timestamp '2014-2-27 1:1:1')::date);

6.创建存储过程使用for遍历某个表

create or replace function mianshi_func01() returns void as $$

declare

--l_id tb_tree.id%type;

--l_pid tb_tree.pid%type;

--l_name tb_tree.name%type;

l_record RECORD;

begin

for l_record in select * from tb_tree loop

raise info 'ID%,父ID%,名称%',l_record.id,l_record.pid,l_record.name;

end loop;

end;

$$ language plpgsql;

7.使用游标遍历某个表

create or replace function mianshi_func02() returns void as $$

declare

l_id tb_tree.id%type;

l_pid tb_tree.pid%type;

l_name tb_tree.name%type;

l_cursor cursor for select * from tb_tree;

begin

open l_cursor;

fetch l_cursor into l_id,l_pid,l_name;

while found loop

raise info 'ID%,父ID%,名称%',l_id,l_pid,l_name;

fetch l_cursor into l_id,l_pid,l_name;

end loop;

close l_cursor;

end;

$$ language plpgsql;

8.备份数据库完成后删除数据库

pg_dump -f another.bak mianshi

drop database mianshi;