Project: StarRocks (App Definition and Development / Database)
File: overview-of-json-functions-and-operators.md

displayed_sidebar: "English" This topic provides an overview of the JSON constructor functions, query functions, and processing functions, operators, and path expressions that are supported by StarRocks. JSON constructor functions are used to construct JSON data, such as JSON objects and JSON arrays. | Function | Description | Example | Return value | | | | | -- | | | Converts one or more key-value pairs to a JSON object that consists of the key-value pairs, which are sorted by key in dictionary order. | `SELECT JSON_OBJECT('Daniel Smith', 26, 'Lily Smith', 25);` | `{"Daniel Smith": 26, "Lily Smith": 25}` | | | Converts each element of an SQL array to a JSON value and returns a JSON array that consists of those JSON values. | `SELECT JSON_ARRAY(1, 2, 3);` | `[1,2,3]` | | | Converts a string to a JSON value. | `SELECT PARSE_JSON('{"a": 1}');` | `{"a": 1}` | JSON query functions and processing functions are used to query and process JSON data. For example, you can use a path expression to locate an element in a JSON object. | Function | Description | Example | Return value | | | | - | - | | | Queries the element that can be located by a path expression in a JSON object. | `SELECT parse_json('{"a": {"b": 1}}') -> '$.a.b';` | `1` | | | Converts data between a JSON data type and an SQL data type. | `SELECT CAST(1 AS JSON);` | `1` | | | Analyzes and gets the floating point value from a specified path in a JSON string. | `SELECT getjsondouble('{"k1":1.3, "k2":"2"}', "$.k1");` | `1.3` | | | Analyzes and gets the integer value from a specified path in a JSON string. | `SELECT getjsonint('{"k1":1, "k2":"2"}', "$.k1");` | `1` | | | Analyzes and gets the strings from a specified path in a JSON string. | `SELECT getjsonstring('{"k1":"v1", "k2":"v2"}', "$.k1");` | `v1` | | | Queries the value of an element that can be located by a path expression in a JSON object. | `SELECT JSON_QUERY('{"a": 1}', '$.a');` | `1` | | | Expands the top-level elements of a JSON object into key-value

| `SELECT * FROM tjtest, LATERAL JSONEACH(j);` | `!` | | | Checks whether a JSON object contains an element that can be located by a path expression. If the element exists, this function returns 1. If the element does not exist, the function returns 0. | `SELECT JSON_EXISTS('{"a": 1}', '$.a'); ` | `1` | | | Returns the top-level keys from a JSON object as a JSON array, or, if a path is specified, the top-level keys from the path. | `SELECT JSON_KEYS('{"a": 1, "b": 2, "c": 3}');` | `["a", "b", "c"]`| | | Returns the length of a JSON document. | `SELECT json_length('{"Name": "Alice"}');` | `1` | | | Converts the JSON object to a JSON string | `SELECT jsonstring(parsejson('{"Name": "Alice"}'));` | `{"Name": "Alice"}` | StarRocks supports the following JSON comparison operators: `<`, `<=`, `>`, `>=`, `=`, and `!=`. You can use these operators to query JSON data. However, it does not allow you to use `IN` to query JSON data. For more information about JSON operators, see . You can use a JSON path expression to query an element in a JSON object. JSON path expressions are of the STRING data type. In most cases, they are used with various JSON functions, such as JSON_QUERY. In StarRocks, JSON path expressions do not completely comply with the . For information about the JSON path syntax that is supported in StarRocks, see the following table, in which the following JSON object is used as an example. ```JSON { "people": [{ "name": "Daniel", "surname": "Smith" }, { "name": "Lily", "surname": "Smith", "active": true }] } ``` | JSON path symbol | Description | JSON path example | Return value | | - | | | | | `$` | Denotes a root JSON object. | `'$'` | `{ "people": [ { "name": "Daniel", "surname": "Smith" }, { "name": "Lily", "surname": Smith, "active": true } ] }`| |`.` | Denotes a child JSON object. |`' $.people'` |`[ { "name": "Daniel", "surname": "Smith" }, { "name": "Lily", "surname": Smith, "active": true } ]`| |``.| `'$.people [0]'` | `{ "name": "Daniel", "surname": "Smith" }` | | `[]` | Denotes all elements in an array. | `'$.people[].name'` | `["Daniel", "Lily"]` | | `[start: end]` | Denotes a subset of elements from an array. The subset is specified by the `[start, end]` interval, which excludes the element that is denoted by the end index. | `'$.people[0: 1].name'` | `["Daniel"]` |