Article by Mike Hillyer. Normalizing data is the most effective way to decrease storage requirements and increase data integrity. In this tutorial we cover the basics of data normalization.
Database theory and an online tutorial interface to an Oracle database system, allowing a user to learn SQL interactively. The site automatically checks and marks SQL and gives instant feedback.
Provides ANSI-SQL solutions to common database query/update tasks. These apply to such relational databases as PostGreSQL, MySQL, Microsoft SQL Server, Oracle, Microsoft Access, SQLite.
Help everyone to gain or improve skills in building SQL Data Manipulation Language statements. A rating system is supported for SELECT exercises and certification. SQL handbook. English and Russian versions.