Oracle数据库JSON函数详解与实战记录 |
JSON_VALUE
语法JSON_VALUE(expression, path RETURNING data_type DEFAULT default_value ON ERROR error_clause) 参数说明
示例从 JSON 文档中提取名称为 “name” 的值，并指定返回类型为 SELECT JSON_VALUE('{"name": "John", "age": 30}', '$.name' RETURNING VARCHAR2) AS name
FROM dual;
JSON_QUERY
语法JSON_QUERY(expression, path [ RETURNING data_type ] [ PRETTY ] [ WITH UNIQUE KEYS ] [ error_clause ]) 示例从 JSON 文档中提取地址对象： SELECT JSON_QUERY('{"name": "John", "age": 30, "address": {"city": "New York", "zipcode": "10001"}}', '$.address') AS address
FROM dual;
JSON_TABLE
语法JSON_TABLE(expression, path COLUMNS (column_name column_type PATH 'json_path' [ DEFAULT default_expr ] [ error_clause ] ...) ) 示例将 JSON 数组展开为表格： 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
语法JSON_EXISTS(expression, path [ error_clause ]) 示例检查 JSON 文档中是否存在 “address” 对象： SELECT JSON_EXISTS('{"name": "John", "age": 30, "address": {"city": "New York", "zipcode": "10001"}}', '$.address') AS address_exists
FROM dual;
JSON_OBJECT
语法JSON_OBJECT(key VALUE value [, key VALUE value ] ...) 示例生成一个 JSON 对象： SELECT JSON_OBJECT('name' VALUE 'John', 'age' VALUE 30) AS json_object
FROM dual;
JSON_ARRAY
语法JSON_ARRAY(value [, value ] ...) 示例生成一个 JSON 数组： SELECT JSON_ARRAY('apple', 'banana', 42) AS json_array
FROM dual;
JSON_MERGEPATCH
语法JSON_MERGEPATCH(target, patch) 示例将两个 JSON 文档合并： SELECT JSON_MERGEPATCH('{"name": "John", "age": 30}', '{"age": 31, "city": "New York"}') AS merged_json
FROM dual;
JSON_OBJECTAGG
语法JSON_OBJECTAGG(key, value) 示例将一组键值对聚合成 JSON 对象： SELECT JSON_OBJECTAGG(department_name, department_id) AS departments_json FROM departments GROUP BY some_column; JSON_ARRAYAGG
语法JSON_ARRAYAGG(value) 示例将一组值聚合成 JSON 数组： SELECT JSON_ARRAYAGG(employee_name) AS employees_json FROM employees GROUP BY some_column; JSON_SCALAR
语法JSON_SCALAR(value) 示例将字符串转换为 JSON 标量值： SELECT JSON_SCALAR('Hello, World!') AS json_scalar
FROM dual;
JSON_DATAGUIDE
语法JSON_DATAGUIDE(expression) 示例生成 JSON 数据指南： SELECT JSON_DATAGUIDE('{"name": "John", "age": 30, "address": {"city": "New York", "zipcode": "10001"}}') AS data_guide
FROM dual;
实战应用场景场景一：从复杂 JSON 结构中提取多层嵌套数据假设我们有一个复杂的 JSON 结构，包含嵌套的对象和数组 。我们需要从中提取某些特定的信息并进行统计分析 。 示例数据{
"employees": [
{
"name": "Alice",
"age": 30,
"department": {
"name": "Sales",
"location": "New York"
},
"projects": [
{"name": "Project A", "status": "Completed"},
{"name": "Project B", "status": "Ongoing"}
]
},
{
"name": "Bob",
"age": 35,
"department": {
"name": "HR",
"location": "Chicago"
},
"projects": [
{"name": "Project C", "status": "Ongoing"}
]
}
]
}
查询示例SELECT e.name, e.age, d.name AS department_name, d.location, p.name AS project_name, p.status
FROM json_table t,
JSON_TABLE(t.json_column, '$.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;
场景二：合并和更新 JSON 文档假设我们有两个 JSON 文档，表示不同时间点的用户信息更新 。我们需要合并这些文档以生成最新的用户信息 。 示例数据{
"name": "John",
"age": 30,
"address": {"city": "New York", "zipcode": "10001"}
}
{
"age": 31,
"address": {"city": "San Francisco"}
}
合并示例SELECT JSON_MERGEPATCH('{"name": "John", "age": 30, "address": {"city": "New York", "zipcode": "10001"}}',
'{"age": 31, "address": {"city": "San Francisco"}}') AS merged_json
FROM dual;
结论Oracle 提供了全面的 JSON 函数集，允许开发者高效地处理 JSON 数据 。无论是提取、查询、生成还是合并 JSON 数据，这些函数都能满足各种实际需求 。通过掌握这些函数，开发者可以更好地在 Oracle 数据库中处理和分析 JSON 数据 。希望本文能帮助你更好地理解和应用这些强大的工具 。 到此这篇关于Oracle数据库JSON函数详解与实战记录的文章就介绍到这了,更多相关Oracle JSON 函数详解内容请搜索以前的文章或继续浏览下面的相关文章希望大家以后多多支持！ |
