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title Quickstart for a "Hello World" basic R code execution in T-SQL (SQL Server Machine Learning) | Microsoft Docs
description Quickstart for R script in SQL Server. Learn the basics of calling R script using the sp_execute_external_script system stored procedure in a hello-world exercise.
ms.prod sql
ms.technology machine-learning
ms.date 10/08/2018
ms.topic quickstart
author HeidiSteen
ms.author heidist
manager cgronlun

Quickstart: "Hello world" R script in SQL Server

[!INCLUDEappliesto-ss-xxxx-xxxx-xxx-md-winonly]

SQL Server includes R language support for data science analytics on resident SQL Server data. Your R script can consist of open-source R functions, third-party R libraries, or built-in Microsoft R libraries such as RevoScaleR for predictive analytics at scale.

Script execution is through stored procedures, using either of the following approaches:

In this quickstart, you learn key concepts by running a "Hello World" R script inT-SQL, with an introduction to the sp_execute_external_script system stored procedure.

Prerequisites

This exercise requires access to an instance of SQL Server with one of the following already installed:

  • SQL Server 2017 Machine Learning Services, with the R language installed

  • SQL Server 2016 R Services

    Your SQL Server instance can be in an Azure virtual machine or on-premises. Just be aware that the external scripting feature is disabled by default, so you might need to enable external scripting and verify that SQL Server Launchpad service is running before you start.

  • A tool for running SQL queries. You can use any application that can connect to a SQL Server database and run T-SQL code. SQL professionals can use SQL Server Management Studio (SSMS) or Visual Studio.

For this quickstart, to show how easy it is to run R inside SQL Server, we've used the new mssql extension for Visual Studio Code. VS Code is a free development environment that can run on Linux, macOS, or Windows. The mssql extension is a lightweight extension for running T-SQL queries. To get Visual Studio Code, see Download and install Visual Studio Code. To add the mssql extension, see this article: Use the mssql extension for Visual Studio Code.

Connect to a database and run a Hello World test script

  1. In Visual Studio Code, create a new text file and name it BasicRSQL.sql.

  2. While this file is open, press CTRL+SHIFT+P (COMMAND + P on a macOS), type sql to list the SQL commands, and select CONNECT. Visual Studio Code prompts you to create a profile to use when connecting to a specific database. This is optional, but makes it easier to switch between databases and logins.

    • Choose a server or instance where R in SQL Server has been installed.
    • Use an account that has permissions to create a new database, run SELECT statements, and view table definitions.

  3. If the connection is successful, you should be able to see the server and database name in the status bar, together with your current credentials. If the connection failed, check whether the computer name and server name are correct.

  4. Paste in this statement and run it.

    EXEC sp_execute_external_script
  @language =N'R',
  @script=N'OutputDataSet<-InputDataSet',
  @input_data_1 =N'SELECT 1 AS hello'
  WITH RESULT SETS (([Hello World] int));
GO

Inputs to this stored procedure include:

  • @language parameter defines the language extension to call, in this case, R.
  • @script parameter defines the commands passed to the R runtime. Your entire R script must be enclosed in this argument, as Unicode text. You could also add the text to a variable of type nvarchar and then call the variable.
  • @input_data_1 is data returned by the query, passed to the R runtime, which returns the data to SQL Server as a data frame.
  • WITH RESULT SETS clause defines the schema of the returned data table for SQL Server, adding "Hello World" as the column name, int for the data type.

Results

rsql_basictut_hello1

If you get any errors from this query, rule out any installation issues. Post-install configuration is required to enable use of external code libraries. See Install SQL Server 2017 Machine Learning Services or Install SQL Server 2016 R Services.Likewise, make sure that the Launchpad service is running.

Depending on your environment, you might need to enable the R worker accounts to connect to SQL Server, install additional network libraries, enable remote code execution, or restart the instance after everything is configured. For more information, see R Services Installation and Upgrade FAQ

Tip

In Visual Studio Code, you can highlight the code you want to run and press CTRL+SHIFT+E. If this is too hard to remember, you can change it! See Customize the shortcut key bindings.

rsql-basictut_hello1code

Next steps

Now that you have confirmed your instance is ready to work with R, take a closer look at structuring inputs and outputs.

[!div class="nextstepaction"] Quickstart: Handle inputs and outputs