声明:本PostgreSQl实用指南系列为刘兴(http://deepfuture.iteye.com/)原创,未经笔者授权,任何人和机构不能转载
D:\pgsql>psql mydb
psql (8.4.2)
Type "help" for help.
删除记录
mydb=# delete from citys where name='北京';
DELETE 1
基本查询
mydb=# select * from citys
mydb-# ;
name | id
------+----
长沙 | 1
湛江 | 2
(2 rows)
mydb=# select * from student
mydb-# ;
name | age | city
------------+-----+------
deepfuture | 20 | 1
未来 | 20 | 2
张三 | 21 | 1
(3 rows)
mydb=# insert into citys values('上海',3)
mydb-# ;
INSERT 0 1
mydb=# select * from citys;
name | id
------+----
长沙 | 1
湛江 | 2
上海 | 3
(3 rows)
mydb=# select citys.name, count(*) from citys left outer join student on (studen
t.city=citys.id) group by citys.name,student.city;
name | count
------+-------
上海 | 1
湛江 | 1
长沙 | 2
(3 rows)
mydb=# select citys.name, count(student.city) from citys left outer join student
on (student.city=citys.id) group by citys.name,student.city;
name | count
------+-------
上海 | 0
湛江 | 1
长沙 | 2
(3 rows)
创建视图
mydb=# create view citylist as select citys.name as 城市, count(student.city) as
人数 from citys left outer join student on (student.city=citys.id) group by cit
ys.name,student.city;
CREATE VIEW
调用视图
mydb=# select * from citylist
mydb-# ;
城市 | 人数
------+------
上海 | 0
湛江 | 1
长沙 | 2
(3 rows)
mydb=#