How to create JSON federated tables in MySQL

You can use the SQL Gateway to configure a MySQL remoting service and set up federated tables for JSON services. The service is a daemon process that provides a MySQL interface to the CData ODBC Driver for JSON: After you have started the service, you can create a server and tables using the FEDERATED Storage Engine in MySQL. You can then work with JSON services just as you would local MySQL tables.

Connect to JSON Services

If you have not already done so, provide values for the required connection properties in the data source name (DSN). You can use the built-in Microsoft ODBC Data Source Administrator to configure the DSN. This is also the last step of the driver installation. See the "Getting Started" chapter in the help documentation for a guide to using the Microsoft ODBC Data Source Administrator to create and configure a DSN.

See the Getting Started chapter in the data provider documentation to authenticate to your data source: The data provider models JSON APIs as bidirectional database tables and JSON files as read-only views (local files, files stored on popular cloud services, and FTP servers). The major authentication schemes are supported, including HTTP Basic, Digest, NTLM, OAuth, and FTP. See the Getting Started chapter in the data provider documentation for authentication guides.

After setting the and providing any authentication values, set to more closely match the data representation to the structure of your data.

The property is the controlling property over how your data is represented into tables and toggles the following basic configurations.

• Document (default): Model a top-level, document view of your JSON data. The data provider returns nested elements as aggregates of data.
• FlattenedDocuments: Implicitly join nested documents and their parents into a single table.
• Relational: Return individual, related tables from hierarchical data. The tables contain a primary key and a foreign key that links to the parent document.

See the Modeling JSON Data chapter for more information on configuring the relational representation. You will also find the sample data used in the following examples. The data includes entries for people, the cars they own, and various maintenance services performed on those cars.

Configure the SQL Gateway

See the SQL Gateway Overview to set up connectivity to JSON services as a virtual MySQL database. You will configure a MySQL remoting service that listens for MySQL requests from clients. The service can be configured in the SQL Gateway UI.

👁 Creating a MySQL Remoting Service in SQL Gateway (Salesforce is shown)

Create a FEDERATED Server and Tables for JSON Services

After you have configured and started the service, create a FEDERATED server to simplify the process of creating FEDERATED tables:

Create a FEDERATED Server

The following statement will create a FEDERATED server based on the ODBC Driver for JSON. Note that the username and password of the FEDERATED server must match a user account you defined on the Users tab of the SQL Gateway.

CREATE SERVER fedJSON
FOREIGN DATA WRAPPER mysql
OPTIONS (USER 'sql_gateway_user', PASSWORD 'sql_gateway_passwd', HOST 'sql_gateway_host', PORT ####, DATABASE 'CData JSON Sys');

Create a FEDERATED Table

To create a FEDERATED table using our newly created server, use the CONNECTION keyword and pass the name of the FEDERATED server and the remote table (people). Refer to the following template for the statement to create a FEDERATED table:

CREATE TABLE fed_people (
 ...,
 [ personal.name.first ] TYPE(LEN),
 [ personal.name.last ] TYPE(LEN),
 ...,
)
ENGINE=FEDERATED
DEFAULT CHARSET=latin1
CONNECTION='fedJSON/people';

NOTE: The table schema for the FEDERATED table must match the remote table schema exactly. You can always connect directly to the MySQL remoting service using any MySQL client and run a SHOW CREATE TABLE query to get the table schema.

Execute Queries

You can now execute queries to the JSON FEDERATED tables from any tool that can connect to MySQL, which is particularly useful if you need to JOIN data from a local table with data from JSON. Refer to the following example:

SELECT 
 fed_people.[ personal.name.first ], 
 local_table.custom_field 
FROM 
 local_table 
JOIN 
 fed_people 
ON 
 local_table.foreign_[ personal.name.first ] = fed_people.[ personal.name.first ];