"firstName": "Henriette Thaulow", "gender": "female", "grade": 5, id int identity constraint PK_JSON_ID primary key,ĭoc nvarchar(max) CONSTRAINT CHECK (ISJSON(doc)>0) Since Sql Server does not have collections we will create simple table that would contain documents same as in the I have used DocumentDB as a reference because it has easy-to-understand syntax, so I believe that you will easily understand how to use equivalent Sql Server queries.ĭocumentDB stores JSON documents in collections. In this post, I will show you some queries that can be executed in DocumentDB and equivalent Sql Server queries. Sql Server provides built-in functions for accessing JSON fields (JSON_VALUE), fragments (JSON_QUERY) and opening JSON documents (OPENJSON). Being a database designed for JSON and JavaScript, DocumentDB uses JavaScript as its underlying type system and supports both SQL as well as JavaScript queries.īoth SQL Server 2016 and DocumentDB enable you to query JSON documents.DocumentDB has nice syntax for querying JSON documents – you can find some good examples on JSON can be used with all components/features in SQL Server such as In-memory OLTP, Column store, temporal, etc.ĭocumentDB is a write optimized and schema agnostic document database purpose built for JSON and JavaScript it does not require any schema or secondary indices in order to serve queries. JSON support in SQL Server uses standard T-SQL syntax for querying JSON data with some additional built-in functions that enables you to read values of objects from JSON data. SQL Server 2016/Azure SQL Db are relational databases that will have support for handling JSON data. In this article I will show you similarities and differences between SQl Server JSON and DocumentDB query syntax. Object or array cannot be found in the specified JSON path.SQL Server JSON query syntax compared to DocumentDB Result: Msg 13624, Level 16, State 2, Line 1 JSON_VALUE('', 'strict $.Name') AS 'JSON_QUERY' Here’s an example to demonstrate the difference between these functions when trying to extract a scalar value. JSON_VALUE() returns a single text value of type nvarchar(4000).JSON_QUERY() returns a JSON fragment of type nvarchar(max).Return ValuesĪnd one more difference is in their return values. So you must provide both arguments when using this function. However, the path argument is a required argument when using the JSON_VALUE() function. That’s because this function can return a whole JSON document if required. Those square brackets around the path argument mean that it’s an optional argument. Syntax DifferencesĪnother difference is in the syntax: JSON_QUERY ( expression ) One extracts an object or an array, the other extracts a scalar value. So the difference between these two functions is what they extract. JSON_VALUE() Extracts a scalar value from a JSON string. Here’s how the two functions are defined: JSON_QUERY() Extracts an object or an array from a JSON string. These two functions have slightly different definitions, a slightly different syntax, and their return values are slightly different. This article looks at the difference between JSON_QUERY() and JSON_VALUE(). There’s definitely a place for both functions when working with JSON and SQL Server. Their general syntax is similar, and at first glance, you might think they do exactly the same thing, but they don’t. These functions can be used to extract data from JSON documents. Two of the many T-SQL functions available in SQL Server are JSON_QUERY() and JSON_VALUE().
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