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JSON_OBJECTAGG (Transact-SQL)

  • Article
  • 01/21/2025

Applies to: Azure SQL Database Azure SQL Managed Instance SQL analytics endpoint and Warehouse in Microsoft Fabric

Constructs a JSON object from an aggregation of SQL data or columns.

The key/value pairs can be specified as input values, column, variable references.

To create a JSON array from an aggregate instead, use JSON_ARRAYAGG.

Note

Both json aggregate functions JSON_OBJECTAGG and JSON_ARRAYAGG are currently in preview for Azure SQL Database, Azure SQL Managed Instance (configured with the Always-up-to-date update policy), and Fabric Data Warehouse.

Transact-SQL syntax conventions

Syntax

JSON_OBJECTAGG ( json_key_value [ json_null_clause ] )
 
json_key_value ::= <json_name> : <value_expression> 

json_null_clause ::= NULL ON NULL | ABSENT ON NULL

Arguments

json_key_value

The key / value pair of the JSON object.

json_null_clause

Optional. Omits the entire property of an object if the value is NULL, or use JSON null as property value. If omitted, NULL ON NULL is default.

Examples

Example 1

The following example returns a JSON object with one key and null value.

select JSON_OBJECTAGG ( 'key':null )

Result

{"key":null}

Example 2

The following example constructs a JSON object with three properties from a result set.

SELECT JSON_OBJECTAGG( c1:c2 )
FROM (
    VALUES('key1', 'c'), ('key2', 'b'), ('key3','a')
) AS t(c1, c2);

Result

{"key1":"c","key2":"b","key3":"a"}

Example 3

The following example returns a result with two columns. The first column contains the object_id value. The second column contains a JSON object where the key is the column name and value is the column_id.

SELECT TOP(5) c.object_id, JSON_OBJECTAGG(c.name:c.column_id) AS columns
  FROM sys.columns AS c
 GROUP BY c.object_id;

Result

object_id column_list
3 {"bitpos":12,"cid":6,"colguid":13,"hbcolid":3,"maxinrowlen":8,"nullbit":11,"offset":10,"ordkey":7,"ordlock":14,"rcmodified":4,"rscolid":2,"rsid":1,"status":9,"ti":5}
5 {"cmprlevel":9,"fgidfs":7,"fillfact":10,"idmajor":3,"idminor":4,"lockres":17,"maxint":13,"maxleaf":12,"maxnullbit":11,"minint":15,"minleaf":14,"numpart":5,"ownertype":2,"rcrows":8,"rowsetid":1,"rsguid":16,"scope_id":18,"status":6}
6 {"cloneid":6,"dbfragid":8,"id":1,"partid":3,"rowsetid":7,"segid":5,"status":9,"subid":2,"version":4}
7 {"auid":1,"fgid":5,"ownerid":3,"pcdata":10,"pcreserved":11,"pcused":9,"pgfirst":6,"pgfirstiam":8,"pgroot":7,"status":4,"type":2}
8 {"fileid":2,"filename":4,"name":3,"status":1}

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