Postgresql Json Sql

a detailed website about json sql query; official website: here, chinese version: here

Json query: ->element_name or index; and can be sequential; 

select column::json->'element' as readdata from schema.tableName;
select column1::json->'element1' as readdata1, column2::json->'element2' as readdata2 from schema.tableName;

 using json function to do operations. 

select description::json->'data'->(JSON_ARRAY_LENGTH(description::json->'data')-1)->0 as readtime from leanheat.lh_demo_ecl_aggregatedata

Examples of json operation(增删改查)：from here

CREATE TABLE leanheat.TActivity (

 id bigint  PRIMARY KEY,-- 活动id

 title character varying(128) NOT NULL,-- 活动名称  

 pricepackage jsonb NOT NULL -- 价格套餐,格式如：[{"packagename":"成人票","price":25,"stock":1000},{"packagename":"儿童票（12岁以下）","price":15,"stock":1000}]

)WITH (

 OIDS=FALSE

);

insert data; and update one data in jsonb field. 

insert into leanheat.TActivity values(1,'演出活动标题1','[{"packagename":"成人票","price":189,"stock":100},{"packagename":"儿童票（12岁以下）","price":66,"stock":20},{"packagename":"成人+儿童套票","price":128,"stock":10}]');

update leanheat.tactivity set pricepackage = pricepackage || '{"packagename":"成人票新增3","price":189,"stock":100}'  where id = 1;

 update;

update leanheat.lh_demo_ecl_aggregateData set description = jsonb_insert(description, '{description, data}', '{"data":[1568898000,29.232178],"data":[1568901600,29.232]}'::jsonb, true)
where description::jsonb->>'series_id' = 'TE8'

jsonb_insert(
    target jsonb,          -> The JSONB data target.
    path text[],           -> The path on the target where the new_value will be inserted.
    new_value jsonb,       -> The new value/key to be inserted.
    [insert_after boolean] -> If true, new_value will be inserted after the target path.
                              And before, if it´s set to false. Default is false.
    )

update leanheat.tactivity set pricepackage = jsonb_set(pricepackage,'{0}','{"price":189,"packagename":"成人票00","stock":100}',false) where id = 1

update leanheat.tactivity set pricepackage = jsonb_set(pricepackage,'{0,packagename}','"成人票000"',false) where id = 1

 delete content of tables. 

delete from leanheat.tactivity;  --delete the content of table.

insert into leanheat.TActivity values(1,'演出活动标题1','[{"packagename":"成人票","price":189,"stock":100},{"packagename":"儿童票（5-15岁）","price":66,"stock":20},{"packagename":"成人+儿童套票","price":128,"stock":10}]');

insert into leanheat.TActivity values(2,'演出活动标题2','[{"packagename":"成人票","price":99,"stock":100},{"packagename":"儿童票（3-5岁）","price":58,"stock":20},{"packagename":"成人+儿童套票","price":99,"stock":10}]');

 drop table; 

DROP TABLE table_name; --drop table.

Indexing; 简介

CREATE INDEX index_name ON table_name (id);  -- create index in a column (id). 

要删除索引，请使用 DROP INDEX 命令。可以随时向表中添加索引或从表中删除索引。

---

One problem of jsonb_insert();

update leanheat.lh_demo_ecl_aggregateData set description = jsonb_insert(description, '{data}', '{"data":[[1568898000,29.232178],[1568901600,29.232]]}'::jsonb, true)
where description::jsonb->>'series_id' = 'TE8'

ERROR: cannot replace existing key HINT: Try using the function jsonb_set to replace key value. 因为已经有data的key了，所以不能再插入key为data的数据了。

update leanheat.lh_demo_ecl_aggregateData set description = jsonb_insert(description, '{data,0}', '{"data":[[1568898000,29.232178],[1568901600,29.232]]}'::jsonb, true)
where description::jsonb->>'series_id' = 'TE8'

改变路径，则会变为以下结果：

加引号的方式，会为如下后面的结果。

update leanheat.lh_demo_ecl_aggregateData set description = jsonb_insert(description, '{data,0}', '"[1568898000,29.232178],[1568901600,29.232]"'::jsonb, true)
where description::jsonb->>'series_id' = 'TE8'

改变插入方式为插入数组。

update leanheat.lh_demo_ecl_aggregateData set description = jsonb_insert(description, '{data,0}', to_jsonb(ARRAY[[1568898000,29.232178],[1568901600,29.232]]), true)
where description::jsonb->>'series_id' = 'TE9'

只插入一个数组，成功！

update leanheat.lh_demo_ecl_aggregateData set description = jsonb_insert(description, '{data,0}', to_jsonb(ARRAY[1568898000,29.232178]), true)
where description::jsonb->>'series_id' = 'TE9'