JSON_QUERY (Transact-SQL)

THIS TOPIC APPLIES TO: yesSQL Server (starting with 2016)yesAzure SQL DatabasenoAzure SQL Data Warehouse noParallel Data Warehouse

Extracts an object or an array from a JSON string.

To extract a scalar value from a JSON string, see JSON_VALUE (Transact-SQL). For info about the differences between JSON_VALUE and JSON_QUERY, see Compare JSON_VALUE and JSON_QUERY.

Topic link icon 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.

JSON_QUERY returns an error if it finds JSON that is not valid in expression before it finds the value identified by path. 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.

path
A JSON path that specifies the object or the array to extract. If it is not specified, JSON from the input will be returned (default value for path is '$'). The JSON path can specify lax or strict mode for parsing. Lax mode is the default and is assumed if the parsing mode is not specified. For more info, see JSON Path Expressions (SQL Server).

In SQL Server 2017 and in Azure SQL Database, you can provide a variable as the value of path.

JSON_QUERY returns an error if the format of path isn't valid.

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.

Remarks

Consider the following JSON text:

{
    "info": {
        "type": 1,
        "address": {
            "town": "Bristol",
            "county": "Avon",
            "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).

Path Return value in lax mode Return value in strict mode More info
$ Returns the entire JSON text. Returns the entire JSON text. N/a
$.info.type NULL Error Not an object or array.

Use JSON_VALUE instead.
$.info.address.town NULL Error Not an object or array.

Use JSON_VALUE instead.
$.info."address" N'{ "town":"Bristol", "county":"Avon", "country":"England" }' N'{ "town":"Bristol", "county":"Avon", "country":"England" }' N/a
$.info.tags N'[ "Sport", "Water polo"]' N'[ "Sport", "Water polo"]' N/a
$.info.type[0] NULL Error Not an array.
$.info.none NULL Error Property does not exist.

Examples

Example 1

The following example shows how to return a JSON fragment from 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
Note

JSON_QUERY returns a valid JSON fragment so FOR JSON will not treat result of JSON_QUERY as a plain text and it will not escape characters returned by JSON_QUERY using JSON escaping rules. If you have JSON stored in column (Tags column in this example) or if you need to dynamically create JSON using some expression, you should wrap it with JSON_QUERY without path parameter if you are returning results using FOR JSON clause.

See Also

JSON Path Expressions (SQL Server)
JSON Data (SQL Server)