这篇文章主要讲解了“怎么使用PostgreSQL的SQL/JSON函数”，文中的讲解内容简单清晰，易于学习与理解，下面请大家跟着小编的思路慢慢深入，一起来研究和学习“怎么使用PostgreSQL的SQL/JSON函数”吧！
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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)感谢各位的阅读，以上就是“怎么使用PostgreSQL的SQL/JSON函数”的内容了，经过本文的学习后，相信大家对怎么使用PostgreSQL的SQL/JSON函数这一问题有了更深刻的体会，具体使用情况还需要大家实践验证。这里是创新互联，小编将为大家推送更多相关知识点的文章，欢迎关注！
