Solutions:

1.
MERGE INTO products_delta AS target
USING products_staging AS source
ON target.SKU_Code = source.SKU_Code
WHEN MATCHED THEN
  UPDATE SET *
WHEN NOT MATCHED THEN
  INSERT *

2.
MERGE INTO sales_delta AS target
USING sales_daily AS source
ON target.Sale_ID = source.Sale_ID
WHEN MATCHED THEN
  UPDATE SET *
WHEN NOT MATCHED THEN
  INSERT *

3.
SET spark.databricks.delta.schema.autoMerge.enabled = true;

MERGE INTO customers_delta AS target
USING customers_enriched AS source
ON target.Customer_ID = source.Customer_ID
WHEN MATCHED THEN
  UPDATE SET *
WHEN NOT MATCHED THEN
  INSERT *

4.
MERGE INTO dim_customers_delta AS target
USING stg_customers AS source
ON target.Customer_ID = source.Customer_ID
WHEN MATCHED THEN
  UPDATE SET
    target.Customer_Name = source.Customer_Name,
    target.Email = source.Email,
    target.Phone = source.Phone,
    target.Update_Date = current_date()
WHEN NOT MATCHED THEN
  INSERT (Customer_ID, Customer_Name, Email, Phone, Create_Date, Update_Date)
  VALUES (source.Customer_ID, source.Customer_Name, source.Email, source.Phone, current_date(), current_date())

5.
MERGE INTO inventory_delta AS target
USING inventory_updates AS source
ON target.SKU_Code = source.SKU_Code
WHEN MATCHED THEN
  UPDATE SET target.Stock_Qty = target.Stock_Qty + source.Quantity_Change
WHEN NOT MATCHED THEN
  INSERT (SKU_Code, Stock_Qty)
  VALUES (source.SKU_Code, source.Quantity_Change)

6.
MERGE INTO pricing_delta AS target
USING pricing_updates AS source
ON target.SKU_Code = source.SKU_Code
WHEN MATCHED AND source.Update_Type = 'Price_Increase' THEN
  UPDATE SET target.Final_MRP = target.Final_MRP * 1.1
WHEN MATCHED AND source.Update_Type = 'Price_Decrease' THEN
  UPDATE SET target.Final_MRP = target.Final_MRP * 0.9
WHEN NOT MATCHED THEN
  INSERT *

7.
MERGE INTO sales_delta AS target
USING sales_incremental AS source
ON target.Sale_ID = source.Sale_ID
WHEN MATCHED THEN
  UPDATE SET *
WHEN NOT MATCHED THEN
  INSERT *
;

-- Check operation metrics
DESCRIBE HISTORY sales_delta

8.
MERGE INTO products_delta AS target
USING products_deletes AS source
ON target.SKU_Code = source.SKU_Code
WHEN MATCHED THEN
  UPDATE SET target.is_deleted = true,
             target.deleted_date = current_date()

9.
WITH combined_sales AS (
  SELECT * FROM online_sales
  UNION ALL
  SELECT * FROM store_sales
)
MERGE INTO consolidated_sales_delta AS target
USING combined_sales AS source
ON target.Sale_ID = source.Sale_ID
WHEN MATCHED THEN
  UPDATE SET *
WHEN NOT MATCHED THEN
  INSERT *

10.
MERGE INTO customer_orders_delta AS target
USING order_updates AS source
ON target.Customer_ID = source.Customer_ID 
   AND target.Order_Date = source.Order_Date
   AND target.Product_ID = source.Product_ID
WHEN MATCHED AND source.Status = 'Cancelled' THEN
  DELETE
WHEN MATCHED THEN
  UPDATE SET target.Quantity = source.Quantity,
             target.Amount = source.Amount
WHEN NOT MATCHED THEN
  INSERT *

11.
ALTER TABLE products_delta ADD CONSTRAINT valid_weight CHECK (Weight > 0);

MERGE INTO products_delta AS target
USING products_updates AS source
ON target.SKU_Code = source.SKU_Code
WHEN MATCHED THEN
  UPDATE SET *
WHEN NOT MATCHED THEN
  INSERT *

12.
MERGE INTO sales_delta AS target
USING late_arriving_sales AS source
ON target.Sale_ID = source.Sale_ID
WHEN MATCHED THEN
  UPDATE SET *
WHEN NOT MATCHED THEN
  INSERT *

13.
-- First, check historical version
SELECT * FROM sales_delta VERSION AS OF 5
WHERE Sale_ID = 'SALE001';

-- Merge correction
MERGE INTO sales_delta AS target
USING data_corrections AS source
ON target.Sale_ID = source.Sale_ID
WHEN MATCHED THEN
  UPDATE SET target.Gross_Amount = source.Corrected_Amount

14.
MERGE INTO cdc_target_delta AS target
USING cdc_stream AS source
ON target.ID = source.ID
WHEN MATCHED AND source.operation = 'DELETE' THEN
  DELETE
WHEN MATCHED AND source.operation = 'UPDATE' THEN
  UPDATE SET *
WHEN NOT MATCHED AND source.operation = 'INSERT' THEN
  INSERT *

15.
-- Optimize table before merge
OPTIMIZE large_sales_delta
ZORDER BY (Sale_Date, Customer_ID);

-- Perform merge operation
MERGE INTO large_sales_delta AS target
USING daily_sales AS source
ON target.Sale_ID = source.Sale_ID
WHEN MATCHED THEN
  UPDATE SET *
WHEN NOT MATCHED THEN
  INSERT *