GET_JSON_OBJECT
Function statement:
GET_JSON_OBJECT(<json> string, <path> string)
Supported engines: SparkSQL and Presto
Usage instructions: Extract JSON object.
Return type: string
Example:
> SELECT get_json_object('{"a":"b"}', '$.a');
b
JSON_TUPLE
Function statement:
JSON_TUPLE(<json> string, <p1> string, ..., <pn> string)
Supported engine: SparkSQL
Usage instructions: Return a tuple similar to the function get_json_object, but it requires multiple input names. All input parameters and output column types are strings.
Return type: struct<string, ..., string>
Example:
> SELECT json_tuple('{"a":1, "b":2}', 'a', 'b');
1 2
TO_JSON
Function statement:
TO_JSON(<expr> struct|map|array[, <option> map])
Supported engines: SparkSQL and Presto
Usage instructions: Return a JSON string with the given structured value.
Return type: string
Example:
> SELECT to_json(named_struct('a', 1, 'b', 2));
{"a":1,"b":2}
> SELECT to_json(named_struct('time', to_timestamp('2015-08-26', 'yyyy-MM-dd')), map('timestampFormat', 'dd/MM/yyyy'));
{"time":"26/08/2015"}
> SELECT to_json(array(named_struct('a', 1, 'b', 2)));
[{"a":1,"b":2}]
> SELECT to_json(map('a', named_struct('b', 1)));
{"a":{"b":1}}
> SELECT to_json(map(named_struct('a', 1),named_struct('b', 2)));
{"[1]":{"b":2}}
> SELECT to_json(map('a', 1));
{"a":1}
> SELECT to_json(array((map('a', 1))));
[{"a":1}]
FROM_JSON
Function statement:
FROM_JSON(<json> string, <schema> string[, <options> map<string, string>])
Supported engines: SparkSQL and Presto
Usage instructions: Return a structured value with the given jsonStr and schema.
Return type: struct
Example:
> SELECT from_json('{"a":1, "b":0.8}', 'a INT, b DOUBLE');
{"a":1,"b":0.8}
> SELECT from_json('{"time":"26/08/2015"}', 'time Timestamp', map('timestampFormat', 'dd/MM/yyyy'));
{"time":2015-08-26 00:00:00}
SCHEMA_OF_JSON
Function statement:
SCHEMA_OF_JSON(<json> string[, <options> map<string, string>])
Supported engine: SparkSQL
Usage instructions: Return the DDL-formatted schema of the JSON string.
Return type: string
Example:
> SELECT schema_of_json('[{"col":0}]');
ARRAY<STRUCT<`col`: BIGINT>>
> SELECT schema_of_json('[{"col":01}]', map('allowNumericLeadingZeros', 'true'));
ARRAY<STRUCT<`col`: BIGINT>>
JSON_ARRAY_LENGTH
Function statement:
JSON_ARRAY_LENGTH(<jsonArray> string)
Supported engines: SparkSQL and Presto
Usage instructions: Return the number of elements in the outermost JSON array.
Return type: integer
Example:
> SELECT json_array_length('[1,2,3,4]');
4
> SELECT json_array_length('[1,2,3,{"f1":1,"f2":[5,6]},4]');
5
> SELECT json_array_length('[1,2');
NULL
JSON_OBJECT_KEYS
Function statement:
JSON_OBJECT_KEYS(<json> string)
Supported engines: SparkSQL and Presto
Usage instructions: Return all keys of the outermost JSON object as an array.
Return type: array<string>
Example:
> SELECT json_object_keys('{}');
[]
> SELECT json_object_keys('{"key": "value"}');
["key"]
> SELECT json_object_keys('{"f1":"abc","f2":{"f3":"a", "f4":"b"}}');
["f1","f2"]
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