PostgreSQL中Json类型使用

一、创建测试表

CREATE TABLE job( jobid SERIAL primary key , jobdesc json)

二、选择符

->(返回对象类型)->>(返回字符型)#>>(选择数组类型)

三、插入选择更新删除操作记录

1.插入记录

insert into job(jobdesc) values('{
        "jobname":"linux_os_vmstat",
        "schedule":{
            "type":{"interval":"5m" },
            "start":"now","end":"None"
        },"values":{
            "event":["cpu_r","cpu_w"], "data":["cpu_r"], "threshold":[1,1]
        },"objects":{
            "wintest1":"cpu"
        }
}');

insert into job(jobdesc) values('{
        "jobname":"[Oracle](http://www.linuxidc.com/topicnews.aspx?tid=12)_tbs_space",
        "schedule":{
            "type":{"interval":"1d"},
            "start":"now","end":"None"},
            "values":{"event":["used"],"data":["used"],"threshold":["90%"]},
            "objects":{"wintest1":"oradb1"}
}');

2.选择记录

select jobdesc->>'jobname' as jobname from job where jobdesc->'objects'->>'wintest1' like 'oradb1';

result:

jobname
oracle_tbs_space
(1 行记录)

select jobdesc->'objects' as objects from job where jobdesc->>'jobname' = 'linux_os_vmstat';  

result:

objects
{ "wintest1":"cpu"}
(1 行记录)

3.数组元素选择

select jobdesc->'values'#>>'{event,0}' as value1 from job where jobdesc->>'jobname' = 'linux_os_vmstat';

result:

value1
cpu_r
(1 行记录)

select jobdesc->'values'#>>'{event,1}' as value2 from job where jobdesc->>'jobname' = 'linux_os_vmstat';

result:

value2
cpu_w
(1 行记录)

4.更新记录

update job set jobdesc = '{
        "jobname":"linux_os_vmstat",
        "schedule":{
            "type":{"interval":"5m"},
            "start":"now",
            "end":"None"
        },"values":{
            "event":["cpu_r","cpu_w"],
            "data":["cpu_r"],
            "threshold":[1,2]
        },
        "objects":{"wintest1":"cpu"}
}' where jobdesc->>'jobname' = 'linux_os_vmstat';

UPDATE 1#

select jobdesc->'values'#>>'{threshold,1}' as threshold2 from jobwhere jobdesc->>'jobname' = 'linux_os_vmstat';

result:

threshold2
2
(1 行记录)

注：更新json类型字段时必须整个字段都更新，无法采用指定内部特定值方法更新。

5.删除记录

select * from job;

result:

|jobid | jobdesc|
|------------------------------------------|
|3 | {"jobname":"oracle_tbs_space","schedule":{+"type":{"interval":+"1d"},"start":"now","end":"None"},"values":{"event":["used"],"data":["used"],"threshold":["90%"]},"objects":{"wintest1":"oradb1"}}|
|4 | {"jobname":"linux_os_vmstat","schedule":{"type":{"interval":"5m"},"start":"now","end":"None"},"values":{"event":["cpu_r","cpu_w"],"data":["cpu_r"],"threshold":[1,1]}"objects":{"wintest1":"cpu"}}|

(2 行记录)

delete from job where jobdesc->>'jobname' = 'linux_os_vmstat';

DELETE 1

select * from job;

result:

|jobid | jobdesc|
|------------------------------------------|
|3 | {"jobname":"oracle_tbs_space","schedule":{+"type":{"interval":+"1d"},"start":"now","end":"None"},"values":{"event":["used"],"data":["used"],"threshold":["90%"]},"objects":{"wintest1":"oradb1"}}|

(1 行记录)

文章转载自：http://www.linuxidc.com/Linux/2013-12/94354.htm