format-json-output-automatically-with-auto-mode-sql-server.md

title	Format JSON Output Automatically with AUTO Mode (SQL Server) | Microsoft Docs
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Format JSON Output Automatically with AUTO Mode (SQL Server)

[!INCLUDEtsql-appliesto-ss2016-asdb-xxxx-xxx_md]

To format the output of the FOR JSON clause automatically based on the structure of the SELECT statement, specify the AUTO option.

When you specify the AUTO option, the format of the JSON output is automatically determined based on the order of columns in the SELECT list and their source tables. You can't change this format.

The alternative is to use the PATH option to maintain control over the output.

• For more info about the PATH option, see Format Nested JSON Output with PATH Mode.
• For an overview of both options, see Format Query Results as JSON with FOR JSON.

A query that uses the FOR JSON AUTO option must have a FROM clause.

Here are some examples of the FOR JSON clause with the AUTO option.

Examples

Example 1

Query

When a query references only one table, the results of the FOR JSON AUTO clause are similar to the results of FOR JSON PATH . In this case, FOR JSON AUTO doesn't create nested objects. The only difference is that FOR JSON AUTO outputs dot-separated aliases (for example, Info.MiddleName in the following example) as keys with dots, not as nested objects.

SELECT TOP 5   
       BusinessEntityID As Id,  
       FirstName, LastName,  
       Title As 'Info.Title',  
       MiddleName As 'Info.MiddleName'  
   FROM Person.Person  
   FOR JSON AUTO  

Result

[{
	"Id": 1,
	"FirstName": "Ken",
	"LastName": "Sánchez",
	"Info.MiddleName": "J"
}, {
	"Id": 2,
	"FirstName": "Terri",
	"LastName": "Duffy",
	"Info.MiddleName": "Lee"
}, {
	"Id": 3,
	"FirstName": "Roberto",
	"LastName": "Tamburello"
}, {
	"Id": 4,
	"FirstName": "Rob",
	"LastName": "Walters"
}, {
	"Id": 5,
	"FirstName": "Gail",
	"LastName": "Erickson",
	"Info.Title": "Ms.",
	"Info.MiddleName": "A"
}]

Example 2

Query

When you join tables, columns in the first table are generated as properties of the root object. Columns in the second table are generated as properties of a nested object. The table name or alias of the second table (for example, D in the following example) is used as the name of the nested array.

SELECT TOP 2 SalesOrderNumber,  
        OrderDate,  
        UnitPrice,  
        OrderQty  
FROM Sales.SalesOrderHeader H  
   INNER JOIN Sales.SalesOrderDetail D  
     ON H.SalesOrderID = D.SalesOrderID  
FOR JSON AUTO   

Result

[{
	"SalesOrderNumber": "SO43659",
	"OrderDate": "2011-05-31T00:00:00",
	"D": [{
		"UnitPrice": 24.99,
		"OrderQty": 1
	}]
}, {
	"SalesOrderNumber": "SO43659",
	"D": [{
		"UnitPrice": 34.40
	}, {
		"UnitPrice": 134.24,
		"OrderQty": 5
	}]
}]

Example 3

Query
Instead of using FOR JSON AUTO, you can nest a FOR JSON PATH subquery in the SELECT statement, as shown in the following example. This example outputs the same result as the preceding example.

SELECT TOP 2  
    SalesOrderNumber,  
    OrderDate,  
    (SELECT UnitPrice, OrderQty  
      FROM Sales.SalesOrderDetail AS D  
      WHERE H.SalesOrderID = D.SalesOrderID  
     FOR JSON PATH) AS D  
FROM Sales.SalesOrderHeader AS H  
FOR JSON PATH  

Result

[{
	"SalesOrderNumber": "SO43659",
	"OrderDate": "2011-05-31T00:00:00",
	"D": [{
		"UnitPrice": 24.99,
		"OrderQty": 1
	}]
}, {
	"SalesOrderNumber": "SO4390",
	"D": [{
		"UnitPrice": 24.99
	}]
}]

Learn more about the built-in JSON support in SQL Server

For lots of specific solutions, use cases, and recommendations, see the blog posts about the built-in JSON support in SQL Server and in Azure SQL Database by Microsoft Program Manager Jovan Popovic.

See Also

FOR Clause (Transact-SQL)