PostgreSQL 12提供了SQL/JSON函数用以兼容SQL 2016 SQL/JSON特性. 这些函数包括: ``` [local]:5432 pg12@testdb=# \df jsonb_path* List of functions Schema | Name | Result data type | Argument data types | Type ------------+------------------------+------------------+-------------------------------------------------------------------------------------------+------ pg_catalog | jsonb_path_exists | boolean | target jsonb, path jsonpath, vars jsonb DEFAULT '{}'::jsonb, silent boolean DEFAULT false | func pg_catalog | jsonb_path_exists_opr | boolean | jsonb, jsonpath | func pg_catalog | jsonb_path_match | boolean | target jsonb, path jsonpath, vars jsonb DEFAULT '{}'::jsonb, silent boolean DEFAULT false | func pg_catalog | jsonb_path_match_opr | boolean | jsonb, jsonpath | func pg_catalog | jsonb_path_query | SETOF jsonb | target jsonb, path jsonpath, vars jsonb DEFAULT '{}'::jsonb, silent boolean DEFAULT false | func pg_catalog | jsonb_path_query_array | jsonb | target jsonb, path jsonpath, vars jsonb DEFAULT '{}'::jsonb, silent boolean DEFAULT false | func pg_catalog | jsonb_path_query_first | jsonb | target jsonb, path jsonpath, vars jsonb DEFAULT '{}'::jsonb, silent boolean DEFAULT false | func (7 rows) ``` 简单试用: ``` [local]:5432 pg12@testdb=# CREATE TABLE characters (data jsonb); "weight" : 0.1 }, {"name" : "ring of strength", "weight" : 2.4 } ], "arm_right" : "Sword of flame", "arm_left" : "Shield of faith" } }'); CREATE TABLE Time: 208.690 ms [local]:5432 pg12@testdb=# INSERT INTO characters VALUES (' pg12@testdb'# { "name" : "Yksdargortso", pg12@testdb'# "id" : 1, pg12@testdb'# "sex" : "male", pg12@testdb'# "hp" : 300, pg12@testdb'# "level" : 10, pg12@testdb'# "class" : "warrior", pg12@testdb'# "equipment" : pg12@testdb'# { pg12@testdb'# "rings" : [ pg12@testdb'# { "name" : "ring of despair", pg12@testdb'# "weight" : 0.1 pg12@testdb'# }, pg12@testdb'# {"name" : "ring of strength", pg12@testdb'# "weight" : 2.4 pg12@testdb'# } pg12@testdb'# ], pg12@testdb'# "arm_right" : "Sword of flame", pg12@testdb'# "arm_left" : "Shield of faith" pg12@testdb'# } pg12@testdb'# }'); INSERT 0 1 Time: 3.881 ms [local]:5432 pg12@testdb=# [local]:5432 pg12@testdb=# [local]:5432 pg12@testdb=# SELECT jsonb_path_query(data, '$.equipment.rings[0].name') AS ring_name FROM characters; ring_name ------------------- "ring of despair" (1 row) Time: 10.081 ms [local]:5432 pg12@testdb=# SELECT jsonb_path_query(data, '$.equipment.rings[0].*') AS data FROM characters; data ------------------- "ring of despair" 0.1 (2 rows) Time: 0.687 ms [local]:5432 pg12@testdb=# SELECT jsonb_path_query(data, '$.equipment.rings[*].weight.floor()') AS weight FROM characters; weight -------- 0 2 (2 rows) ``` 如果是PG 11或以下版本,则需要使用#>>等操作符实现 ``` testdb=# select data#>>'{equipment,rings,0,name}' AS ring_name FROM characters; ring_name ----------------- ring of despair (1 row) ``` **参考资料** [Postgres 12 highlight - SQL/JSON path](https://paquier.xyz/postgresql-2/postgres-12-jsonpath/)