InstallSchema and InstallData

In Magento 2, both InstallSchema and InstallData are used to set up the database schema and initial data for your custom module during installation. However, they serve slightly different purposes:

1. InstallSchema:The InstallSchema script is used to define and modify the database schema, including creating new tables or modifying existing ones. It runs only once during the module installation process and is responsible for setting up the structure of your module’s database tables.Use InstallSchema when you need to create or modify database tables, define their columns, indexes, and other structural elements. This is where you define the raw database schema that your module needs.
2. InstallData:The InstallData script is used to insert initial data into the database during the module installation process. It can be used to populate your module’s database tables with sample or default data that your module needs to function properly.Use InstallData when you need to insert initial records, configuration settings, default values, or any data that your module requires to work correctly. This data is inserted into the tables after the table structures have been defined using InstallSchema.

In summary, InstallSchema is used for defining the raw database structure, while InstallData is used for populating that structure with initial data. Both scripts are crucial for setting up your module’s database correctly during installation.