Tag Archives: JSON in Sql Server

JSON_QUERY Function in Sql Server 2016

JSON_QUERY is one of the new JSON function introduced in Sql Server 2016 to query the JSON data. JSON_QUERY basically returns the JSON fragment (i.e. JSON object or an array) from the input JSON string from the specified JSON path.

SYNTAX:

JSON_QUERY ( json_string,  json_path )

WHERE:

json_string is the JSON string from which the JSON fragment will be extracted.

json_path is the location of the JSON string in the json_string. Within json_path we can specify the path mode, it can be lax or strict. Lax is the default path mode, if json_path is invalid (i.e. it is not present in the json_string) then it returns null, but if path mode is strict it will raise an error.

This function will return error even in the scenario if the specified json_path is resulting in a scalar value other than the JSON object or array. Where as JSON_VALUE works the other way, it returns an error in case the JSON path is

[ALSO READ]:

Let us understand JSON_QUERY function with extensive list of examples:

Example 1: In this example let us try to get the Hobbies array using the JSON_QUERY function

DECLARE @json_str NVARCHAR(MAX) = 
 '{"Id":1,"Name":"Basavaraj",
		"Hobbies":["Blogging","Cricket"]}'
SELECT JSON_QUERY(@json_str,'$.Hobbies') Hobbies

RESULT:
JSON_QUERY Sql Example 1 1

Here in the json_path the $ symbol implies the json_string and $. Hobbies means Hobbies property in the json_string at the root level.

Let us try doing the same using the JSON_VALUE function

DECLARE @json_str NVARCHAR(MAX) = 
 '{"Id":1,"Name":"Basavaraj",
		"Hobbies":["Blogging","Cricket"]}'
SELECT JSON_VALUE(@json_str,'$.Hobbies') Hobbies

RESULT:
JSON_QUERY Sql Example 1 2

From the result it is clear that JSON_VALUE function is not for reading the JSON object or array, instead it is for reading the scalar JSON values like string, integer etc.

Example 2: Try to get the complete JSON string from the root

DECLARE @json_str NVARCHAR(MAX) = 
 '{"Id":1,"Name":"Basavaraj",
		"Hobbies":["Blogging","Cricket"]}'
--Get customer details
SELECT JSON_QUERY(@json_str,'$') JSON
GO

RESULT:
JSON_QUERY Sql Example 2

Example 3: Try to get a JSON scalar value (i.e. non-JSON object or array)

DECLARE @json_str NVARCHAR(MAX) = 
 '{"Id":1,"Name":"Basavaraj",
		"Hobbies":["Blogging","Cricket"]}'
SELECT JSON_QUERY(@json_str,'$.Name') Name

RESULT:
JSON_QUERY Sql Example 3
[ALSO READ]:lax and strict JSON Path modes in Sql Server 2016
Example 4: lax and strict JSON path modes in JSON_QUERY

Let us try to re-execute the example 3 by setting the JSON path mode as strict

DECLARE @json_str NVARCHAR(MAX) = 
 '{"Id":1,"Name":"Basavaraj",
		"Hobbies":["Blogging","Cricket"]}'
SELECT JSON_QUERY(@json_str,'strict$.Name') Name

RESULT:

Msg 13608, Level 16, State 2, Line 4
Property cannot be found in specified path.

Let us try executing the above query by explicitly specifying the default JSON path mode lax

DECLARE @json_str NVARCHAR(MAX) = 
 '{"Id":1,"Name":"Basavaraj",
		"Hobbies":["Blogging","Cricket"]}'
SELECT JSON_QUERY(@json_str,'lax$.Name') Name

RESULT:
JSON_QUERY Sql Example 4 2
Example 5: In this example try to read on of the array element which in-turn is not a JSON object or an array

DECLARE @json_str NVARCHAR(MAX) = 
 '{"Id":1,"Name":"Basavaraj",
		"Hobbies":["Blogging","Cricket"]}'
SELECT JSON_QUERY(@json_str,'$.Hobbies[1]') Hobby

RESULT:
JSON_QUERY Sql Example 5 1

Try to execute the above query using the JSON_VALUE function instead of JSON_QUERY function

DECLARE @json_str NVARCHAR(MAX) = 
 '{"Id":1,"Name":"Basavaraj",
		"Hobbies":["Blogging","Cricket"]}'
SELECT JSON_VALUE(@json_str,'$.Hobbies[1]') Hobby

RESULT:
JSON_QUERY Sql Example 5 2

From these examples it is clear that we can use the JSON_QUERY function to extract a JSON object or an array only, but not for the scalar values like string, integer etc.

Example 6: Try to extract complete JSON from the JSON string

DECLARE @json_str NVARCHAR(MAX) = 
 '{"Customers":
	[{"Id":1,"Name":"Basavaraj",
	  "Address":{"State":"KA","Country":"India"}},
	 {"Id":2,"Name":"Kalpana",
	  "Address":{"State":"NY","Country":"United State"}}
	]
 }'
 SELECT JSON_QUERY(@json_str,'$') CompleteJSON

RESULT:
JSON_QUERY Sql Example 6

Example 7: In this example try to extract the Customers array

DECLARE @json_str NVARCHAR(MAX) = 
 '{"Customers":
	[{"Id":1,"Name":"Basavaraj",
			"Address":{"State":"KA","Country":"India"}},
	 {"Id":2,"Name":"Kalpana",
			"Address":{"State":"NY","Country":"United State"}}
	]
 }'
 SELECT JSON_QUERY(@json_str,'$.Customers') CustomersArray

RESULT:
JSON_QUERY Sql Example 7

Example 8: In this example extract the first customer JSON object

DECLARE @json_str NVARCHAR(MAX) = 
 '{"Customers":
	[{"Id":1,"Name":"Basavaraj",
			"Address":{"State":"KA","Country":"India"}},
	 {"Id":2,"Name":"Kalpana",
			"Address":{"State":"NY","Country":"United State"}}
	]
 }'
 SELECT JSON_QUERY(@json_str,'$.Customers[0]') CustomerObject

RESULT:
JSON_QUERY Sql Example 8

Example 9: In this example try to extract the first customer’s address object

DECLARE @json_str NVARCHAR(MAX) = 
 '{"Customers":
	[{"Id":1,"Name":"Basavaraj",
			"Address":{"State":"KA","Country":"India"}},
	 {"Id":2,"Name":"Kalpana",
			"Address":{"State":"NY","Country":"United State"}}
	]
 }'
 SELECT JSON_QUERY(@json_str,'$.Customers[0].Address') AddressObject

RESULT:
JSON_QUERY Sql Example 9

[ALSO READ]:

JSON_VALUE Function in Sql Server 2016

JSON_VALUE is one of the new JSON scalar function introduced in Sql Server 2016. This function returns the scalar value from the input JSON text from the specified JSON path location.

SYNTAX:

JSON_VALUE ( json_string,  json_path )

WHERE:

json_string is the JSON string from which the scalar value will be extracted.

json_path is the location of the scalar value in the json_string. Within json_path we can specify the path mode, it can be lax or strict. Lax is the default path mode, if json_path is invalid (i.e. it is not present in the json_string) then it returns null, but if path mode is strict it will raise an error.

[ALSO READ]:

Let us understand JSON_VALUE function with extensive list of examples:

Basic JSON_VALUE function examples

Example 1: Basic example where we are trying to get FirstName from a JSON string

SELECT 
 JSON_VALUE('{"FirstName":"Basavaraj","Last Name":"Biradar"}',
					'$.FirstName') AS 'First Name'

RESULT:
JSON_VALUE Sql Example 1

Here in the json_path the $ symbol implies the json_string and $.FirstName means FirstName property in the json_string at the root level.

Example 2: Getting FirstName JSON property value which is not at the root level

SELECT JSON_VALUE(
 '{"Name":{"FirstName":"Basavaraj","Last Name":"Biradar"}}',
					'$.Name.FirstName') AS 'First Name'

RESULT:
JSON_VALUE Sql Example 2

Here in this example FirstName property is not at the root level instead it is in the Name object, because of that we need to specify the path as ‘$.Name.FirstName’ instead of just ‘$.FirstName’ like the example 1.

Example 3: Repeat the example 2, but specify the path as in example one. Basically, the idea of this example is to check whether specifying the path like $.PropertyName searches the PropertyName anywhere in the JSON string or just at the root level

SELECT JSON_VALUE(
  '{"Name":{"FirstName":"Basavaraj","Last Name":"Biradar"}}',
					'$.FirstName') AS 'First Name'

RESULT:
JSON_VALUE Sql Example 3

From the result it is clear that, specifying the JSON path like $.PropertyName, just tries to locate the PropertName just at the root level, in otherwords JSON path is the exact location of the string.

Example 4: This example explains that the JSON path expression is case sensitive

SELECT JSON_VALUE('{"name":"Basavaraj"}','$.NAME') AS Name

RESULT:
JSON_VALUE Sql Example 4 1

From the result it is clear that the JSON path is case sensitive. Even though the JSON sting has the property name but the response returned is NULL because the property mentioned in the JSON path is in upper case where as in the JSON string it is in lower case

Let us try the above example by specifying the JSON path in the same case as that in the JSON string

SELECT JSON_VALUE('{"name":"Basavaraj"}','$.name') AS Name

RESULT:
JSON_VALUE Sql Example 4 2

Example 5: This example explains how to specify a JSON String property name with spaces in it in the JSON path expression

Let us try to fetch the JSON property Last Name value, where this property name has an empty space in it:

SELECT JSON_VALUE(
	'{"Last Name":"Basavaraj"}','$.Last Name') AS 'Last Name'

RESULT:

Msg 13607, Level 16, State 4, Line 1
JSON path is not properly formatted. Unexpected character found at position 7.

In case if the JSON property name has a space in it, then while specifying it in the JSON path we need to specify property name by enclosing it in the double quotes.

Let us re-write the query and try now

SELECT JSON_VALUE(
  '{"Last Name":"Basavaraj"}','$."Last Name"') AS 'Last Name'

RESULT:
JSON_VALUE Sql Example 5 2

Advanced JSON_VALUE function examples

Example 1: Reading values from JSON object where one of its property is an Array (i.e. [ , ])

DECLARE @json_str NVARCHAR(MAX) = 
 '{"Id":1,"Name":"Basavaraj",
		"Hobbies":["Blogging","Cricket"]}'
SELECT JSON_VALUE(@json_str,'$.Name') Name,
	JSON_VALUE(@json_str,'$.Hobbies[0]') Hobby1,
	JSON_VALUE(@json_str,'$.Hobbies[1]') Hobby2

RESULT:
JSON_VALUE Sql Advance Example 1

Example 2: Trying to get a non-scalar value. In the below example trying to get the value of a property which is an array

DECLARE @json_str NVARCHAR(MAX) = 
 '{"Id":1,"Name":"Basavaraj",
		"Hobbies":["Blogging","Cricket"]}'
SELECT JSON_VALUE(@json_str,'$.Hobbies') Hobbies

RESULT:
JSON_VALUE Sql Advance Example 2

From the result it is clear that if the JSON Path is pointing to a non-scalar value like an array, sub JSON object etc will return a NULL value or an error if PATH mode is strict. In this example the JSON path is pointing to an array [“Blogging”,”Cricket”] , because of this JSON_VALUE function returning a NULL value

Example 3: Reading JSON property value from a JSON object where Customers property is an array of JSON object (i.e. [{},{}])

DECLARE @json_str NVARCHAR(MAX) = 
 '{"Customers":
	[{"Id":1,"Name":"Basavaraj",
			"Address":{"State":"KA","Country":"India"}},
	 {"Id":2,"Name":"Kalpana",
			"Address":{"State":"NY","Country":"United State"}}
	]
 }'
--Get first customer details
SELECT 
 JSON_VALUE(@json_str,'$.Customers[0].Name') Name,
 JSON_VALUE(@json_str,'$.Customers[0].Address.Country') Country
 --Get second customer details
SELECT 
 JSON_VALUE(@json_str,'$.Customers[1].Name') Name,
 JSON_VALUE(@json_str,'$.Customers[1].Address.Country') Country

RESULT:
JSON_VALUE Sql Advance Example 3

Example 4: A modified version of the example 3

DECLARE @json_str NVARCHAR(MAX) = 
	'{"Customers":
		[{"Customer":{"Id":1,"Name":"Basavaraj",
			"Address":{"State":"KA","Country":"India"}}},
		 {"Customer":{"Id":2,"Name":"Kalpana",
			"Address":{"State":"NY","Country":"United State"}}}
		]
	}'
--Get first customer details
SELECT 
 JSON_VALUE(@json_str,'$.Customers[0].Customer.Name') Name,
 JSON_VALUE(@json_str,
   '$.Customers[0].Customer.Address.Country') Country
 --Get second customer details
SELECT 
 JSON_VALUE(@json_str,'$.Customers[1].Customer.Name') Name,
 JSON_VALUE(@json_str,
   '$.Customers[1].Customer.Address.Country') Country

RESULT:
JSON_VALUE Sql Advance Example 4

[ALSO READ]:

Native JSON Support in Sql Server 2016

Native JSON (Java Script Object Notation) support is one of the new feature that is coming with Sql Server 2016.

Introduction to JSON

JSON is simple data representation format, which readable, portable and platform independent. Now JSON is a popular lightweight data-exchange format between the systems. Prior to JSON, web Services used XML as their primary data format for data-interchange. Now JSON is the preferred data-interchange format used by the Web APIs. To know more on JSON you can visit http://json.org/

JSON Anatomy
JSON Structure

  • JSON Notations
    : JSON Property Name and value (if it is string) is enclosed within double quotes
    : : Colon symbol is used as the separator between the JSON property Name and Value.
    {} : Curly braces symbol represents the objects
    [,] : Arrays of Value
    [{},{}] : Arrays of Objects
  • To know more on JSON you can visit http://json.org/

    JSON In Sql Server 2016

    JSON implementation in Sql server is on the similar lines as that of XML. One major difference is: JSON doesn’t have native JSON data type like the XML data type. We can store JSON data in regular NVARCHAR/VARCHAR column.

    Below are the main JSON features introduced in Sql Server 2016. Click on the link to understand each of these features with an extensive list of examples.

    FOR JSON Clause: can be used to convert the query result (rows) to JSON format.

    OPENJSON Function : is very much similar to the OPENXML function, it provides a rowset view of the JSON. It is basically a table valued function, that can be used to transform the JSON value to one or many rows

    ISJSON Function: This function validates whether the parameter supplied to it is a well formed JSON or not

    JSON_VALUE Function: This function returns the scalar value from the input JSON text from the specified JSON path location

    JSON_QUERY Function: This function extracts the JSON fragment (i.e. JSON object or an array) from the input JSON string from the specified JSON path.

    JSON_MODIFY Function: This function can be used to update the value of the property in a JSON string and returns the updated JSON string.

    Indexing Strategy for JSON Value in Sql Server 2016

    lax and strict JSON Path modes in Sql Server 2016

    [ALSO READ]:

    New features in SQL SERVER 2016