Step 3: Query the Tables in a Ledger - Amazon Quantum Ledger Database (Amazon QLDB)

Step 3: Query the Tables in a Ledger

After creating tables in an Amazon QLDB ledger and loading them with data, you can run queries to review the vehicle registration data that you just inserted. QLDB uses PartiQL as its query language and Amazon Ion as its document-oriented data model.

PartiQL is an open source, SQL-compatible query language that has been extended to work with Ion. With PartiQL, you can insert, query, and manage your data with familiar SQL operators. Amazon Ion is a superset of JSON. Ion is an open source, document-based data format that gives you the flexibility of storing and processing structured, semistructured, and nested data.

In this step, you use SELECT statements to read data from the tables in the vehicle-registration ledger.

To query the tables

  1. Open the Amazon QLDB console at https://console.aws.amazon.com/qldb.

  2. In the navigation pane, choose Query editor.

  3. Choose the vehicle-registration ledger.

  4. In the query editor window, enter the following statement to query the Vehicle table for a particular vehicle identification number (VIN) that you added to the ledger, and then choose Run.

    To run the statement, you can also use the keyboard shortcut Ctrl+Enter for Windows, or Cmd+Return for macOS. For more keyboard shortcuts, see Accessing Amazon QLDB Using the Console.

    SELECT * FROM Vehicle AS v WHERE v.VIN = '1N4AL11D75C109151'
  5. You can write inner join queries. This query example joins Vehicle with VehicleRegistration and returns registration information along with attributes of the registered vehicle for a specified VIN.

    Enter the following statement, and then choose Run.

    SELECT v.VIN, r.LicensePlateNumber, r.State, r.City, r.Owners FROM Vehicle AS v, VehicleRegistration AS r WHERE v.VIN = '1N4AL11D75C109151' AND v.VIN = r.VIN

    You can also join the Person and DriversLicense tables to see attributes related to the drivers who were added to the ledger.

    Repeat this step for the following.

    SELECT * FROM Person AS p, DriversLicense as l WHERE p.GovId = l.LicenseNumber

To learn about modifying documents in the tables in the vehicle-registration ledger, see Step 4: Modify Documents in a Ledger.