Changing data in an existing Delta Lake table

In the previous section, we saw how new data can be written to a Delta Lake table. But transactions in Delta Lake are not only about new data – we may also need to update and delete data as well. In this section, we will find out how the data lake reacts to changes in existing data:

1. To highlight the effect of changes to Delta Lake tables, we will work with a sample row in the store_orders table as follows:

   %sql
   SELECT * FROM store_orders WHERE order_number=5; 

   This results in the following output:

   Figure 6.22 – Checking the data in the sales_orders table for the sample row

2. Now, we will update this row and change the sale_ price value from 98.41 to 90.50:

   %sql
   UPDATE store_orders SET sale_price=90.50 WHERE order_number=5;

3. Check if the sale_ price value got updated in the store_orders table:

   %sql
   SELECT * FROM store_orders WHERE order_number=5;

   This results in the following output:

   Figure 6.23 – Checking the...