Query a price history table for the price effective on each order date, enforce unique starts, and compare APPLY lookups with range joins.
DATE_CORRELATION_OPTIMIZATION: Helping Joins on Related Dates
SQL Server can learn that an order date and a ship date move together. Here is a small demo of the read savings and the trade you accept.
Join Duplicates: Stop Hiding Extra Rows With SELECT DISTINCT
Diagnose join duplicates before using DISTINCT, verify order and payment totals, and choose aggregation or EXISTS for the required result.
What is the Difference Between Physical and Logical Operation in SQL Server Execution Plan? – Interview Question of the Week #122
Question: What is the Difference Between Physical and Logical Operation in SQL Server Execution Plan?
Nullable Foreign Keys: Optional Relationships and Outer Joins
A nullable foreign key lets a row say no relationship yet. I show what the constraint checks, why an inner join drops those rows, and where WHERE bites.
What is a Self Join? Explain with Example – Interview Question of the Week #064
What is a Self Join? It is a popular interview question for every developer. Here is a simple answer, whether it is inner or outer, and a practical use.
Interview Question of the Week #043 – What is the Difference Between EXCEPT operator vs. NOT IN
Compare EXCEPT operator vs. NOT IN using NULL and duplicate examples, add NOT EXISTS, and inspect actual SQL Server anti-join plans.