Through the many changes in IT over the years, one constant has always been a concern for performance. With database systems there is especially true. Even with the many advances in relational ...

Read this SQL tutorial to learn when to use SELECT, JOIN, subselects and UNION to access multiple tables with a single statement. It’s sometimes difficult to know which SQL syntax to use when ...

A common SQL habit is to use SELECT * on a query, because it’s tedious to list all the columns you need. Plus, sometimes those columns may change over time, so why not just do things the easy way? But ...