The add-in can return JSON structures as column values. The add-in enables you to use standard SQL functions to work with these JSON structures. The examples in this section use the following array:

[
     { "grade": "A", "score": 2 },
     { "grade": "A", "score": 6 },
     { "grade": "A", "score": 10 },
     { "grade": "A", "score": 9 },
     { "grade": "B", "score": 14 }
]

JSON_EXTRACT

The JSON_EXTRACT function can extract individual values from a JSON object. The following query returns the values shown below based on the JSON path passed as the second argument to the function:

SELECT Name, JSON_EXTRACT(grades,'[0].grade') AS Grade, JSON_EXTRACT(grades,'[0].score') AS Score FROM Students;

Column Name	Example Value
Grade	A
Score	2

JSON_COUNT

The JSON_COUNT function returns the number of elements in a JSON array within a JSON object. The following query returns the number of elements specified by the JSON path passed as the second argument to the function:

SELECT Name, JSON_COUNT(grades,'[x]') AS NumberOfGrades FROM Students;

Column Name	Example Value
NumberOfGrades	5

JSON_SUM

The JSON_SUM function returns the sum of the numeric values of a JSON array within a JSON object. The following query returns the total of the values specified by the JSON path passed as the second argument to the function:

SELECT Name, JSON_SUM(score,'[x].score') AS TotalScore FROM Students;

Column Name	Example Value
TotalScore	41

JSON_MIN

The JSON_MIN function returns the lowest numeric value of a JSON array within a JSON object. The following query returns the minimum value specified by the JSON path passed as the second argument to the function:

SELECT Name, JSON_MIN(score,'[x].score') AS LowestScore FROM Students;

Column Name	Example Value
LowestScore	2

JSON_MAX

The JSON_MAX function returns the highest numeric value of a JSON array within a JSON object. The following query returns the maximum value specified by the JSON path passed as the second argument to the function:

SELECT Name, JSON_MAX(score,'[x].score') AS HighestScore FROM Students;

Column Name	Example Value
HighestScore	14

DOCUMENT

The DOCUMENT function can be used to return an document as a JSON string. DOCUMENT(*) can be used with any type of SELECT query, including queries including other columns, queries including just DOCUMENT(*), and even more complex queries like JOINs.

SELECT [Document.Id], grade, score, DOCUMENT(*) FROM grades

For example, that query would return:

Document.Id	grade	score	DOCUMENT
1	A	6	{"document.id":1,"grade":"A","score":6}
2	A	10	{"document.id":1,"grade":"A","score":10}
3	A	9	{"document.id":1,"grade":"A","score":9}
4	B	14	{"document.id":1,"grade":"B","score":14}

When used alone, DOCUMENT(*) returns the structure directly from Couchbase as if a N1QL or SQL++ SELECT * query were used. This means that no Document.Id value will be present since Couchbase does not include it automatically.

SELECT DOCUMENT(*) FROM grades

This query would return:

DOCUMENT
{"grades":{"grade":"A","score":6"}}
{"grades":{"grade":"A","score":10"}}
{"grades":{"grade":"A","score":9"}}
{"grades":{"grade":"B","score":14"}}