Why create and use child databases within databases?

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In some use cases, it is essential to create a distinction within the same database.

If we want to split a database into two, we will need to create two child databases.

1. What is a child database within databases?

Ermeo allows you to create databases. All resources present in the same database will have the same attributes.

In a database, we can define child databases also called "sub-databases".

In this case, there will be an inheritance of attributes. The existing attributes for the database will also exist for the child databases.

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2. In practice, how to create child databases?

Context: Let's imagine a company that inspects thousands of rails across Europe. These rails are resources stored in a database called "Rails".

Each resource in the database will be characterized by the following attributes:

  • Rail Length
  • Rail Thickness
  • Rail Year

The company wants to add an attribute to qualify the rail standard. This standard is not the same between France and England.

We will create a first child database named 'Rails England". This child database will have the attribute "England Standard".

Then, we will create a second child database named "Rails France". This child database will have the attribute "France Standard".

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  1. In the Databases tab, click on New Database.
  2. Create a new database. Name it "Rails". Do not choose a parent database.
  3. Add the following attributes:
  • Rail Length (of Number type)
  • Rail Thickness (of Number type)
  • Rail Year (of Number type)
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4. Go back to the Databases list and create a new database. Name it Rails France. Select the newly created "Rails" database as the parent database.

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  1. Based on the Rails France database, add an attribute of type Multiple Choices and name it "Norme France".

Enter the following values for multiple choices:

  • NF 1435 mm
  • NF 1700 mm
  1. Repeat operation 6 by replacing the term France with England. Enter the following values for multiple choices:
  • NUK 1524 mm
  • NUK 1628 mm

You have created your two child databases "Rails France" and "Rails England". These two sub-databases appear in the "Rails" database.

You can now create resources in each of the sub-databases.

  • The resources created in the sub-database "Rails England" will have the attribute "Norme England".
  • The resources created in the sub-database "Rails France" will have the attribute "Norme France".