Oracle数据库JSON函数详解与实战记录

JSON_VALUE(expression, path RETURNING data_type DEFAULT default_value ON ERROR error_clause)

SELECT JSON_VALUE('{"name": "John", "age": 30}', '$.name' RETURNING VARCHAR2) AS name
FROM dual;

JSON_QUERY(expression, path [ RETURNING data_type ] [ PRETTY ] [ WITH UNIQUE KEYS ] [ error_clause ])

SELECT JSON_QUERY('{"name": "John", "age": 30, "address": {"city": "New York", "zipcode": "10001"}}', '$.address') AS address
FROM dual;

JSON_TABLE(expression, path
  COLUMNS (column_name column_type PATH 'json_path' [ DEFAULT default_expr ] [ error_clause ] ...)
)

SELECT jt.title, jt.key, jt.level
FROM json_table,
     JSON_TABLE(json_column, '$[*]'
       COLUMNS (
         title VARCHAR2(100) PATH '$.title',
         key VARCHAR2(50) PATH '$.key',
         level NUMBER PATH '$.level'
       )
     ) jt;

JSON_EXISTS(expression, path [ error_clause ])

SELECT JSON_EXISTS('{"name": "John", "age": 30, "address": {"city": "New York", "zipcode": "10001"}}', '$.address') AS address_exists
FROM dual;

JSON_OBJECT(key VALUE value [, key VALUE value ] ...)

SELECT JSON_OBJECT('name' VALUE 'John', 'age' VALUE 30) AS json_object
FROM dual;

JSON_ARRAY(value [, value ] ...)

SELECT JSON_ARRAY('apple', 'banana', 42) AS json_array
FROM dual;

JSON_MERGEPATCH(target, patch)

SELECT JSON_MERGEPATCH('{"name": "John", "age": 30}', '{"age": 31, "city": "New York"}') AS merged_json
FROM dual;

JSON_OBJECTAGG(key, value)

SELECT JSON_OBJECTAGG(department_name, department_id) AS departments_json
FROM departments
GROUP BY some_column;

JSON_ARRAYAGG(value)

SELECT JSON_ARRAYAGG(employee_name) AS employees_json
FROM employees
GROUP BY some_column;

JSON_SCALAR(value)

SELECT JSON_SCALAR('Hello, World!') AS json_scalar
FROM dual;

JSON_DATAGUIDE(expression)

SELECT JSON_DATAGUIDE('{"name": "John", "age": 30, "address": {"city": "New York", "zipcode": "10001"}}') AS data_guide
FROM dual;

{
  "employees": [
    {
      "name": "Alice",
      "age": 30,
      "department": {
        "name": "Sales",
        "location": "New York"
      },
      "projects": [
        {"name": "Project A", "status": "Completed"},
        {"name": "Project B", "status": "Ongoing"}
      ]
    },
    {
      "name": "Bob",
      "age": 35,
      "department": {
        "name": "HR",
        "location": "Chicago"
      },
      "projects": [
        {"name": "Project C", "status": "Ongoing"}
      ]
    }
  ]
}

SELECT e.name, e.age, d.name AS department_name, d.location, p.name AS project_name, p.status
FROM json_table t,
     JSON_TABLE(t.json_column, '$.employees[*]'
       COLUMNS (
         name VARCHAR2(50) PATH '$.name',
         age NUMBER PATH '$.age',
         NESTED PATH '$.department' COLUMNS (
           department_name VARCHAR2(50) PATH '$.name',
           location VARCHAR2(50) PATH '$.location'
         ),
         NESTED PATH '$.projects[*]' COLUMNS (
           project_name VARCHAR2(50) PATH '$.name',
           status VARCHAR2(20) PATH '$.status'
         )
       )
     ) e;

{
  "name": "John",
  "age": 30,
  "address": {"city": "New York", "zipcode": "10001"}
}

{
  "age": 31,
  "address": {"city": "San Francisco"}
}

SELECT JSON_MERGEPATCH('{"name": "John", "age": 30, "address": {"city": "New York", "zipcode": "10001"}}',
                       '{"age": 31, "address": {"city": "San Francisco"}}') AS merged_json
FROM dual;