-- we are going to add return reason in orders tables, this will show all colums from orders and all columns from returns -- this will show all data which is matching, and neglect the null value ...

It is a SQL practice repository covering basics to advanced topics. It includes exercises on SELECT statements, WHERE clauses, GROUP BY, JOINS, window functions (OVER(), PARTITION BY), ROW_NUMBER(), ...

Assuring optimal performance of database applications starts with coding properly formulated SQL. Poorly written SQL and application code is the cause of most performance problems. As much as 75% of ...

Whether you’re just getting in to programming or you’ve avoided learning SQL, it’s something every developer faces eventually. You may not be responsible for building and maintaining a database, but ...

Learn how to master the SELECT statement to form truly useful data queries. This article explains functions, clauses, and keywords that will make your life a lot easier. Due to popular demand, we’re ...