1. Create db_schema.xml File

In Magento 2.3 and later, it's recommended to use the db_schema.xml file to define database tables. If you're using an older version of Magento 2, you can use an InstallSchema.php script instead.

Step 1: Create db_schema.xml

Create the app/code/Vendor/ModuleName/etc/db_schema.xml file:
  
<?xml version="1.0"?>
<schema xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Setup/Declaration/Schema/etc/schema.xsd">
<table name="vendor_modulename_custom_table" resource="default" engine="innodb" comment="Custom Table">
    <column xsi:type="int" name="entity_id" nullable="false" identity="true" unsigned="true" primary="true" comment="Entity ID"/>
    <column xsi:type="varchar" name="name" nullable="false" length="255" comment="Name"/>
    <column xsi:type="text" name="description" nullable="true" comment="Description"/>
    <column xsi:type="timestamp" name="created_at" nullable="false" default="CURRENT_TIMESTAMP" on_update="false" comment="Creation Time"/>
    <column xsi:type="timestamp" name="updated_at" nullable="false" default="CURRENT_TIMESTAMP" on_update="true" comment="Update Time"/>
    <constraint xsi:type="primary" referenceId="PRIMARY">
        <column name="entity_id"/>
    </constraint>
</table>
</schema>

Step 2: Explanation

  • <table>: Defines the table name, storage engine (innodb), and a comment describing the table.
  • <column>: Defines each column's data type, name, whether it can be null, and any additional options like default values or comments.
  • <constraint>: Defines constraints such as primary keys or foreign keys.