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Azure SQL Managed Instance
Azure Synapse Analytics
Extracts an object or an array from a JSON string.
To extract a scalar value from a JSON string instead of an object or an array, see
JSON_VALUE (Transact-SQL)
. For info about the differences between
JSON_VALUE
and
JSON_QUERY
, see
Compare JSON_VALUE and JSON_QUERY
.
Transact-SQL syntax conventions
Syntax
JSON_QUERY ( expression [ , path ] )
Arguments
expression
An expression. Typically the name of a variable or a column that contains JSON text.
If JSON_QUERY finds JSON that is not valid in expression before it finds the value identified by path, the function returns an error. If JSON_QUERY doesn't find the value identified by path, it scans the entire text and returns an error if it finds JSON that is not valid anywhere in expression.
A JSON path that specifies the object or the array to extract.
In SQL Server 2017 (14.x) and in Azure SQL Database, you can provide a variable as the value of path.
The JSON path can specify lax or strict mode for parsing. If you don't specify the parsing mode, lax mode is the default. For more info, see JSON Path Expressions (SQL Server).
The default value for path is '$'. As a result, if you don't provide a value for path, JSON_QUERY returns the input expression.
If the format of path isn't valid, JSON_QUERY returns an error.
Return value
Returns a JSON fragment of type nvarchar(max). The collation of the returned value is the same as the collation of the input expression.
If the value is not an object or an array:
In lax mode, JSON_QUERY returns null.
In strict mode, JSON_QUERY returns an error.
Lax mode and strict mode
Consider the following JSON text:
"info": {
"type": 1,
"address": {
"town": "Cheltenham",
"county": "Gloucestershire",
"country": "England"
"tags": ["Sport", "Water polo"]
"type": "Basic"
The following table compares the behavior of JSON_QUERY in lax mode and in strict mode. For more info about the optional path mode specification (lax or strict), see JSON Path Expressions (SQL Server).
Return value in lax mode
Return value in strict mode
More info
$.info."address"
N'{ "town":"Cheltenham", "county":"Gloucestershire", "country":"England" }'
N'{ "town":"Cheltenham", "county":"Gloucestershire", "country":"England" }'
$.info.tags
N'[ "Sport", "Water polo"]'
N'[ "Sport", "Water polo"]'
$.info.type[0]
Error
Not an array.
$.info.none
Error
Property does not exist.
Using JSON_QUERY with FOR JSON
JSON_QUERY returns a valid JSON fragment. As a result, FOR JSON doesn't escape special characters in the JSON_QUERY return value.
If you're returning results with FOR JSON, and you're including data that's already in JSON format (in a column or as the result of an expression), wrap the JSON data with JSON_QUERY without the path parameter.
Examples
Example 1
The following example shows how to return a JSON fragment from a CustomFields
column in query results.
SELECT PersonID,FullName,
JSON_QUERY(CustomFields,'$.OtherLanguages') AS Languages
FROM Application.People
Example 2
The following example shows how to include JSON fragments in the output of the FOR JSON clause.
SELECT StockItemID, StockItemName,
JSON_QUERY(Tags) as Tags,
JSON_QUERY(CONCAT('["',ValidFrom,'","',ValidTo,'"]')) ValidityPeriod
FROM Warehouse.StockItems
FOR JSON PATH
See also
JSON Path Expressions (SQL Server)
JSON Data (SQL Server)