JSON_EXTRACT_<type>

Extracts data from JSON, optionally based on a path specification.

When used with JSON object or array and a path specification, extracts data from the JSON object or array that matches the path specification. Will return NULL if the path is not matched or if either of the arguments are NULL.

When used with a JSON argument and no path specification, extracts data from the JSON to a value of <type>. With this usage, it is possible to extract from JSON string, numeric, boolean, and NULL values in addition to extracting from JSON objects and arrays.

The following JSON_EXTRACT_<type> functions are supported:

  • JSON_EXTRACT_DOUBLE is for all numeric data (equivalent to the ::% JSON operator).

  • JSON_EXTRACT_STRING is for all text and binary types (equivalent to the ::$ JSON operator). The result collation is controlled by the json_extract_string_collation engine variable. Refer to Sync Variables Lists for more information.

  • JSON_EXTRACT_JSON is for all valid JSON types, including true, false, JSON maps, and JSON lists.

  • JSON_EXTRACT_BIGINT is for all BIGINT types. Other data types are handled as follows: Booleans (true and false) become 1 and 0, respectively. Floats are rounded as follows: 1.4 becomes 1, while 1.5 becomes 2. For all other data types, 0 is returned.

    Note

    For more information on JSON operators ::, ::$, and ::%, see Accessing Fields in a JSON Object. Also, see Character Encodings and Collation for information on overriding collation settings.

Syntax

JSON_EXTRACT_<type>(<json>, <keypath> [, ]);
JSON_EXTRACT_<type>(<json>);

Arguments

  • json: valid JSON, or the name of a JSON column.

  • keypath: (optional) The path specification; a comma-separated list of object keys or zero-indexed array positions.

Return Value

When JSON_EXTRACT_<type> is used with a JSON object or array literal and a path specification, the return values are as listed below. Refer to JSON_EXTRACT_<type> with Path Specification for more details.

  • SQL-NULL if value is JSON NULL (such as {"a": null}), or if keyname does not exist.

  • The extracted element if <json> is a valid JSON object or array and the path specified by the list of <keypath>s exists in <json>.

  • SQL-NULL if <json> is not a valid JSON object or array or if the path specified by the list of <keypaths> does not exist in <json>.

  • SQL-NULL if <json> is SQL-NULL, an empty string, a JSON string, a JSON number, a JSON boolean value, or an empty JSON object or array.

  • JSON-null for JSON_EXTRACT_JSON if the value is JSON-null (such as {"a": null}).

  • SQL-NULL for JSON_EXTRACT_STRING if the value is JSON-null (such as {"a": null}).

  • 0 for JSON_EXTRACT_BIGINT and JSON_EXTRACT_DOUBLE if the value is JSON-null (such as {"a": null}).

Refer to JSON_EXTRACT_<type> - JSON Argument Only the return values of JSON_EXTRACT_<type> when used with a JSON argument only.

JSON_EXTRACT_<type> with Path Specification

The following table summarizes the functionality and return types of JSON_EXTRACT_<type> when both a JSON object or array literal and a path specification are provided as arguments.

<json>

Function

Return

Comments

JSON Object

or

Array Literal

JSON_EXTRACT_JSON(<json>, <keypath> [,...])

json

or

SQL-NULL

Extracts the JSON value found at the path (<keypath> [,...]). Value returned as JSON.

If the extracted object is a JSON string, quotes are not removed.

Returns SQL-NULL if keypath is not found.

JSON_EXTRACT_STRING(<json>, <keypath> [,...])

string

or

SQL-NULL

Extracts the JSON value found at the path (<keypath> [,...]). Value returned as a string.

If the extracted object is a JSON string, quotes are removed. 

Returns SQL-NULL if keypath is not found.

JSON_EXTRACT_BIGINT(<json>, <keypath> [,...])

integer

or

0

If the extracted value is a JSON string, extracts a valid numeric prefix and rounds to an Integer. Value returned as a BIGINT.

Otherwise, returns 0.

JSON_EXTRACT_DOUBLE(<json>, <keypath> [,...])

double

or

0

If the extracted value is a JSON string, extracts a valid numeric prefix. Value returned as DOUBLE.

Otherwise, returns 0.

JSON_EXTRACT_<type> - JSON Argument Only

The following table summarizes the functionality and return values of JSON_EXTRACT_<type> over a JSON argument only.

For all functions, the return value matches the type of the function. JSON_EXTRACT_JSON returns a JSON value, JSON_EXTRACT_STRING returns a string value, and so on.

<json>

Function

Return

Notes

SQL-NULL

JSON_EXTRACT_<type>(NULL)

SQL-NULL

Empty string

JSON_EXTRACT_<type>('')

SQL-NULL

JSON-null

JSON_EXTRACT_JSON('null')

JSON-null

Returns JSON-null

JSON_EXTRACT_STRING('null')

JSON_EXTRACT_BIGINT('null')

JSON_EXTRACT_DOUBLE('null')

SQL-NULL

Empty JSON Object

JSON_EXTRACT_JSON('{}')

{}

Returns JSON value.

JSON_EXTRACT_STRING('{}')

{}

Returns string value.

JSON_EXTRACT_BIGINT('{}')

JSON_EXTRACT_DOUBLE('{}')

0

Return value matches type of function.

JSON boolean value

JSON_EXTRACT_JSON('true')

JSON_EXTRACT_JSON('false')

true

false

Returns JSON value.

JSON_EXTRACT_STRING('true')

JSON_EXTRACT_STRING('false')

true

false

Returns string value.

JSON_EXTRACT_BIGINT('true')

JSON_EXTRACT_DOUBLE('true')

JSON_EXTRACT_BIGINT('false')

JSON_EXTRACT_DOUBLE('false')

1

0

Returns 1 for true, 0 for false.

Return value matches type of function.

JSON string

JSON_EXTRACT_JSON('"<string>"')

"<string>"

Does not remove quotes.

JSON_EXTRACT_STRING('"<string>"')

<string >

Removes quotes.

JSON_EXTRACT_BIGINT('"<string>"')

JSON_EXTRACT_DOUBLE('"<string>"')

numeric prefix

or

0

If string has a valid numeric prefix, returns the numeric prefix, rounded appropriately.

Returns 0 if the string does not have a valid numeric prefix.

JSON number

JSON_EXTRACT_JSON('<numeric>')

numeric value

Returns JSON value.

JSON_EXTRACT_STRING('<numeric>')

numeric value

Returns string value.

JSON_EXTRACT_BIGINT('<numeric>')

rounded numeric value

Returns BIGINT.

JSON_EXTRACT_DOUBLE('<numeric>')

numeric value

Returns DOUBLE.

JSON object

JSON_EXTRACT_JSON(<json object>)

JSON_EXTRACT_STRING(<json object>)

<json object>

Extracts full object.

JSON_EXTRACT_BIGINT(<json object>)

JSON_EXTRACT_DOUBLE(<json object>)

0

Return value matches type of function.

JSON array

JSON_EXTRACT_JSON(<json array>)

JSON_EXTRACT_STRING(<json array˘>)

<json array>

Extracts full array.

JSON_EXTRACT_BIGINT(<json array>)

JSON_EXTRACT_DOUBLE(<json array>)

0

Return value matches type of function.

Invalid JSON

JSON_EXTRACT_JSON(<invalid json>)

JSON_EXTRACT_STRING(<invalid json>)

SQL-NULL

JSON_EXTRACT_BIGINT(<invalid json>)

JSON_EXTRACT_DOUBLE(<invalid json>)

0

Multi-Argument Examples

Example 1

Extracts the value for beta.

SELECT JSON_EXTRACT_DOUBLE('{"alpha":1, "beta":2, "gamma": [3,4,5]}', 'beta')
AS get_beta;
+----------+
| get_beta |
+----------+
|        2 |
+----------+

Example 2

Extracts value for 1 from an array.

SELECT JSON_EXTRACT_DOUBLE('[3,4,5]', 1) AS get_result;
+------------+
| get_result |
+------------+
|          4 |
+------------+

Note

Since JSON uses zero-indexed array positions, extracting with the path 0 will extract the value 3 and the path 1 will extract the value 4 as in the example above.

Example 3

Extracts the value for the path gamma.

SELECT JSON_EXTRACT_JSON('{"alpha":1, "beta":2, "gamma": [3,4,5]}', 'gamma')
AS get_gamma;
+-----------+
| get_gamma |
+-----------+
| [3,4,5]   |
+-----------+

Example 4

Extracts the value for the path gamma.1. Since arrays use zero-based indexing, the function will extract the number in the first position of the array [3,4,5] which is 4 in this example.

SELECT JSON_EXTRACT_JSON('{"alpha":1, "beta":2, "gamma": [3,4,5]}', 'gamma', 1)
AS get_gamma;
+-----------+
| get_gamma |
+-----------+
| 4         |
+-----------+

Example 5

The result in the following example is NULL as zeta has no value.

SELECT JSON_EXTRACT_JSON('{"alpha":1, "beta":2, "gamma": [3,4,5]}', 'zeta')
AS get_zeta;
+-----------+
| get_zeta  |
+-----------+
| NULL      |
+-----------+

Example 6

The result in the next example is rounded up to the next whole integer. If the value had been 1.25 the result would have been 1.

SELECT JSON_EXTRACT_BIGINT('{"alpha":1, "beta":2, "gamma": [3,4,5], "delta":1.5}', 'delta')
AS get_delta;
+-----------+
| get_delta |
+-----------+
| 2         |
+-----------+

Example 7

The value for the path gamma is an array so the entire array is returned as a string value.

SELECT JSON_EXTRACT_STRING('{"alpha":1, "beta":2, "gamma": [3,4,5]}', 'gamma')
AS get_gamma;
+-----------+
| get_gamma |
+-----------+
| [3,4,5]   |
+-----------+

Example 8

Returns the value for the path gamma which is a non-numeric string in this example.

SELECT JSON_EXTRACT_STRING('{"alpha":1, "beta":2, "gamma": "A string"}', 'gamma')
AS get_gamma;
+-----------+
| get_gamma |
+-----------+
| A string  |
+-----------+

Single Argument Examples

Example 1 - JSON_EXTRACT_JSON

Extract from a JSON string with " " quotes. The JSON_EXTRACT_JSON function does not remove the " " quotes from the string.

SELECT JSON_EXTRACT_JSON('"a string"');
+---------------------------------------------+
| JSON_EXTRACT_JSON('"a string"')             |
+---------------------------------------------+
|                         "a string"          |
+---------------------------------------------+

Extract from a string without " " quotes.

SELECT JSON_EXTRACT_JSON('a string');
+----------------------------------------+
| JSON_EXTRACT_JSON('a string')          |
+----------------------------------------+
|                         NULL           |
+----------------------------------------+

The JSON_EXTRACT_JSON function with one argument will return the JSON input if the input is valid JSON or SQL-NULL if the input is invalid JSON.

Extract from a JSON array. Will extract the entire array.

SELECT JSON_EXTRACT_JSON('["array element"]');
+----------------------------------------+
| JSON_EXTRACT_JSON('["array element"]') |
+----------------------------------------+
|                   ["array element"]    |
+----------------------------------------+

Extract from a JSON object with two key-value pairs, for which the values are arrays with a single element. The entire JSON object will be extracted.

SELECT JSON_EXTRACT_JSON('{"key2":[2],"key3":[3]}');
+----------------------------------------------+
| JSON_EXTRACT_JSON('{"key2":[2],"key3":[3]}') |
+----------------------------------------------+
|                     {"key2":[2],"key3":[3]}  |
+----------------------------------------------+

Example 2 - JSON_EXTRACT_STRING

Extract from a string. The JSON_EXTRACT_STRING function removes the " " quotes from the string.

SELECT JSON_EXTRACT_STRING('"a string"');
+----------------------------------+
| JSON_EXTRACT_STRING('"a string"')|
+----------------------------------+
|                    a string      |
+----------------------------------+

The JSON_EXTRACT_STRING function will return the JSON input as a string if the input is valid JSON or SQL-NULL if the input is invalid JSON.

Extract from a JSON array with one element which is a string. Will extract the entire array.

SELECT JSON_EXTRACT_STRING('["array element"]');
+------------------------------------------+
| JSON_EXTRACT_STRING('["array element"]') |
+------------------------------------------+
|                     ["array element"]    |
+------------------------------------------+

Extract from a JSON object with two key-value pairs, for which the values are arrays with a single element. The entire JSON object will be extracted.

SELECT JSON_EXTRACT_STRING('{"key2":[2],"key3":[3]}');
+------------------------------------------------+
| JSON_EXTRACT_STRING('{"key2":[2],"key3":[3]}') |
+------------------------------------------------+
|                    {"key2":[2],"key3":[3]}     |
+------------------------------------------------+

Example 3 - JSON_EXTRACT_BIGINT

Extract from a JSON double value. Rounds to the nearest integer.

SELECT JSON_EXTRACT_BIGINT('3.14');
+-------------------------------+
| JSON_EXTRACT_BIGINT('3.14')   |
+-------------------------------+
|                          3    |
+-------------------------------+

Extract from a JSON string with a numeric prefix. Extracts a valid numeric prefix from the string and rounds to the nearest integer.

SELECT JSON_EXTRACT_BIGINT('"12.3a"');
+-------------------------------+
| JSON_EXTRACT_BIGINT('"12.3a"')|
+-------------------------------+
|                       12      |
+-------------------------------+

Example 4 - JSON_EXTRACT_DOUBLE

Extract from a JSON double value.

SELECT JSON_EXTRACT_DOUBLE('3.14');
+-------------------------------+
| JSON_EXTRACT_DOUBLE('3.14')   |
+-------------------------------+
|                          3.14 |
+-------------------------------+

Extract from a JSON string containing a double value. Extracts a valid numeric prefix from the string.

SELECT JSON_EXTRACT_DOUBLE('"12.3a"');
+-------------------------------+
| JSON_EXTRACT_DOUBLE('"12.3a"')|
+-------------------------------+
|                       12.3    |
+-------------------------------+

Last modified: September 30, 2024

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