How to add new Foriegn Key in existing table in Magento 2.4.5

Question

I am trying to add a new foriegn key in existing table using db_schema.xml but it is not working at all I tried to delete the table and delete module from setup_module table as well but still nothing working.

How I can resolve this issue? Thanks!!

Answer 1

Below is an example of using the foreign key as product id with a custom table.

<table name="custom_tab" resource="default" engine="innodb">
  <column xsi:type="int" name="entity_id" padding="10" unsigned="true" nullable="false" identity="true"/>
  <column name="product_id" nullable="true" xsi:type="int" padding="10" identity="false" unsigned="true"/>
  <constraint xsi:type="primary" referenceId="PRIMARY">
    <column name="entity_id"/>
  </constraint>
  <constraint xsi:type="foreign" referenceId="CUSTOM_TABLE_PRODUCT_ID_CATALOG_PRODUCT_ENTITY_ENTITY_ID"
    table="custom_tab" column="product_id"
   referenceTable="catalog_product_entity" referenceColumn="entity_id" onDelete="CASCADE"/>
</table>

Please try like this and inform it is working for you or not ?