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Version: v3.x (DDN)

Get Started with Hasura DDN and SQL Server

Overview​

This tutorial takes about twenty minutes to complete. You'll learn how to:

  • Set up a new Hasura DDN project
  • Connect it to a SQL Server database
  • Generate Hasura metadata
  • Create a build
  • Run your first query
  • Create relationships

Additionally, we'll familiarize you with the steps and workflows necessary to iterate on your API.

This tutorial assumes you're starting from scratch but you can easily follow the steps if you already have data seeded. Hasura will never modify your source schema.

Prerequisites​

Install the DDN CLI

Minimum version requirements

To use this guide, ensure you've installed/updated your CLI to at least v2.28.0.

Simply run the installer script in your terminal:

curl -L https://graphql-engine-cdn.hasura.io/ddn/cli/v4/get.sh | bash
ARM-based Linux Machines

Currently, the CLI does not support installation on ARM-based Linux systems.

Install Docker

The Docker-based workflow helps you iterate and develop locally without deploying any changes to Hasura DDN, making the development experience faster and your feedback loops shorter. You'll need Docker Compose v2.20 or later.

Validate the installation

You can verify that the DDN CLI is installed correctly by running:

ddn doctor

Tutorial​

Step 1. Authenticate your CLI​

Before you can create a new Hasura DDN project, you need to authenticate your CLI:
ddn auth login

This will launch a browser window prompting you to log in or sign up for Hasura DDN. After you log in, the CLI will acknowledge your login, giving you access to Hasura Cloud resources.

Step 2. Scaffold out a new local project​

Next, create a new local project:
ddn supergraph init my-project && cd my-project

Once you move into this directory, you'll see your project scaffolded out for you. You can view the structure by either running ls in your terminal, or by opening the directory in your preferred editor.

Step 3. Start a local SQL Server container​

Start a SQL Server instance
docker pull mcr.microsoft.com/mssql/server:2022-latest
docker run -e "ACCEPT_EULA=Y" -e "MSSQL_SA_PASSWORD=Password123" -p 1433:1433 --name sqlserver -d mcr.microsoft.com/mssql/server:2022-latest

Step 4. Connect and create a table​

docker exec -it sqlserver /opt/mssql-tools18/bin/sqlcmd -S localhost -U sa -P Password123 -C -N
Create a table in the database:
CREATE TABLE users (user_id int primary key, name varchar(255), age int);
GO
Then, seed the table:
INSERT INTO users (user_id, name, age) VALUES (1, 'Alice', 25), (2, 'Bob', 30), (3, 'Charlie', 35);
GO
You can verify this by running:
SELECT * FROM users;
GO

You should see a list of users returned.

Step 4. Initialize your SQL Server connector​

In your project directory, run:
ddn connector init my_sqlserver -i

From the dropdown, start typing sqlserver and hit enter to accept the default port. Then, provide the following values:

Connection string

The connection string format will be in the format Server=<hostname>,<port>;Database=<database>;Uid=<username>;Password=<password> and so is as follows:

Server=local.hasura.dev,1433;Database=master;Uid=sa;Password=Password123;TrustServerCertificate=true
Certificate security

TrustServerCertificate=true should only be added for local databases.

Step 5. Introspect your SQL Server database​

Next, use the CLI to introspect your SQL Server database:
ddn connector introspect my_sqlserver

After running this, you should see a representation of your database's schema in the app/connector/my_sqlserver/configuration.json file; you can view this using cat or open the file in your editor.

Additionally, you can check which resources are available, and their status, at any point using the CLI:
ddn connector show-resources my_sqlserver

Step 6. Add your model​

Now, track the table from your SQL Server database as a model in your DDN metadata:
ddn model add my_sqlserver users

Open the app/metadata directory and you'll find a newly-generated file: Users.hml. The DDN CLI will use this Hasura Metadata Language file to represent the users table from SQL Server in your API as a model.

tip

To track all available models in the dababase, run:

ddn model add my_sqlserver "*"

Step 7. Create a new supergraph build​

To create a local build, run:
ddn supergraph build local

The build is stored as a set of JSON files in engine/build.

Step 8. Start your local services​

Use the docker-start script in the Hasura context to start your local services.

Start your local Hasura DDN Engine and SQL Server connector:
ddn run docker-start

Your terminal will be taken over by logs for the different services.

Step 9. Run your first query​

In a new terminal tab, open your local console:
ddn console --local
In the GraphiQL explorer of the console, write this query:
query {
  users {
    userId
    name
    age
  }
}
You'll get the following response:
{
  "data": {
    "users": [
      {
        "userId": 1,
        "name": "Alice",
        "age": 25
      },
      {
        "userId": 2,
        "name": "Bob",
        "age": 30
      },
      {
        "userId": 3,
        "name": "Charlie",
        "age": 35
      }
    ]
  }
}

Step 10. Iterate on your SQL Server schema​

Let's add a new table for posts:
CREATE TABLE posts (user_id int, post_id int primary key, title varchar(255), content varchar(255), FOREIGN KEY (user_id) REFERENCES users(user_id));
GO
Then, seed it:
INSERT INTO posts (user_id, post_id, title, content) VALUES (1, 1, 'My First Post', 'This is Alice''s first post.'), (1, 2, 'Another Post', 'Alice writes again!'), (2, 3, 'Bob''s Post', 'Bob shares his thoughts.'), (3, 4, 'Hello World', 'Charlie joins the conversation.');
GO
Finally, we can check the posts were generated:
SELECT posts.post_id, posts.title, posts.content, users.name AS author FROM posts JOIN users ON posts.user_id = users.user_id;

Step 11. Refresh your metadata and rebuild your project​

tip

The following steps are necessary each time you make changes to your source schema. This includes, adding, modifying, or dropping tables.

Step 11.1. Re-introspect your data source​

Run the introspection command again:
ddn connector introspect my_sqlserver

In app/connector/my_sqlserver/configuration.json, you'll see schema updated to include operations for the posts table. In app/metadata/my_sqlserver.hml, you'll see posts present in the metadata as well.

Step 11.2. Update your metadata​

Add the posts model:
ddn model add my_sqlserver posts

Step 11.3. Kill your services​

Bring down the services by pressing CTRL+C in the terminal tab logging their activity.

Step 11.4. Create a new build​

Next, create a new build:
ddn supergraph build local

Step 11.5 Restart your services​

Bring everything back up:
ddn run docker-start

Step 12. Query your new build​

Head back to your console and query the posts model:
query GetPosts {
  posts {
    userId
    postId
    title
    content
  }
}
You'll get a response like this:
{
  "data": {
    "posts": [
      {
        "userId": 1,
        "postId": 1,
        "title": "My First Post",
        "content": "This is Alice's first post."
      },
      {
        "userId": 1,
        "postId": 2,
        "title": "Another Post",
        "content": "Alice writes again!"
      },
      {
        "userId": 2,
        "postId": 3,
        "title": "Bob's Post",
        "content": "Bob shares his thoughts."
      },
      {
        "userId": 3,
        "postId": 4,
        "title": "Hello World",
        "content": "Charlie joins the conversation."
      }
    ]
  }
}

Step 13. Create a relationship​

Since there's already a foreign key on the posts table in SQL Server, we can easily add the relationship:
ddn relationship add my_sqlserver posts

You'll see a new metadata object added to the app/metadata/posts.hml file of kind Relationship explaining the relationship between posts and users.

Step 14. Rebuild your project​

Bring down the services by pressing CTRL+C in the terminal tab logging their activity.

As your metadata has changed, create a new build:
ddn supergraph build local
Bring everything back up:
ddn run docker-start

Step 15. Query using your relationship​

Now, execute a nested query using your relationship:
query GetPosts {
  posts {
    postId
    title
    content
    user {
      userId
      name
      age
    }
  }
}
Which should return a result like this:
{
  "data": {
    "posts": [
      {
        "postId": 1,
        "title": "My First Post",
        "content": "This is Alice's first post.",
        "user": {
          "userId": 1,
          "name": "Alice",
          "age": 25
        }
      },
      {
        "postId": 2,
        "title": "Another Post",
        "content": "Alice writes again!",
        "user": {
          "userId": 1,
          "name": "Alice",
          "age": 25
        }
      },
      {
        "postId": 3,
        "title": "Bob's Post",
        "content": "Bob shares his thoughts.",
        "user": {
          "userId": 2,
          "name": "Bob",
          "age": 30
        }
      },
      {
        "postId": 4,
        "title": "Hello World",
        "content": "Charlie joins the conversation.",
        "user": {
          "userId": 3,
          "name": "Charlie",
          "age": 35
        }
      }
    ]
  }
}

Next steps​

Congratulations on completing your first Hasura DDN project with SQL Server! 🎉

Here's what you just accomplished:

  • You started with a fresh project and connected it to a local SQL Server database.
  • You set up metadata to represent your tables and relationships, which acts as the blueprint for your API.
  • Then, you created a build — essentially compiling everything into a ready-to-use API — and successfully ran your first GraphQL queries to fetch data.
  • Along the way, you learned how to iterate on your schema and refresh your metadata to reflect changes.

Now, you're equipped to connect and expose your data, empowering you to iterate and scale with confidence. Great work!

Take a look at our SQL Server docs to learn more about how to use Hasura DDN with SQL Server. Or, if you're ready, get started with adding permissions to control access to your API.

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