Read this SQL tutorial to learn when to use SELECT, JOIN, subselects and UNION to access multiple tables with a single statement.

PolyBase, a data virtualization feature for SQL Server, allows users to seamlessly query data from various external sources directly using T-SQL (Transact-SQL) without the need for separate client ...

SQL Server 2016 and Azure SQL Database both give you tables that automatically keep track of changes to your data. Here's how to both create those tables and alter existing tables so they track the ...

In SQL 7 and other high-end relational databases, each table is required to have a Unique Row Identifier or Primary Key in order to interact with other tables. Access does not require this and will ...

SQL lets you use one command to quickly create a new table containing a subset of records from a larger table while working in Access. Sound complicated? It's not, as Mary Ann Richardson shows us.