Initialization operation
Create table
CREATE TABLE orders ( "ID" int8 NOT NULL,
"info_j" json NOT NULL,
"info_t" text NOT NULL
);
initialization table
INSERT INTO orders("ID", "info_j","info_t") VALUES (1, '{
"name":"张三","items":{
"product":"啤酒","qty":6}}','{
"name":"张三","items":{
"product":"啤酒","qty":6}}');
INSERT INTO orders("ID", "info_j","info_t") VALUES (2, '{
"name":"李四","items":{
"product":"辣条","qty":8}}','{
"name":"李四","items":{
"product":"辣条","qty":8}}');
INSERT INTO orders("ID", "info_j","info_t") VALUES (3, '{
"name":"王五","items":{
"product":"苹果","qty":18}}','{
"name":"王五","items":{
"product":"苹果","qty":18}}');
INSERT INTO orders("ID", "info_j","info_t") VALUES (4, '{
"name":"赵一","items":{
"product":"香蕉","qty":20}}','{
"name":"赵一","items":{
"product":"香蕉","qty":20}}');
lookup table
Parse JSON fields
The query uses the -> operator to query all customers in json as keys
SELECT info_j -> 'name' AS customer FROM orders;
The ->> operation is used below to obtain all customer names as values
SELECT info_j ->> 'name' AS customer FROM orders;
Query the value based on the key of the json object
SELECT info_j -> 'items' ->> 'product' AS customer FROM orders;
Parse JSON fields in TEXT
In fact, just like parsing JSON fields, we only need to add::json
