Welcome to our blog series on SQL Server! In this post, we will discuss some fundamental concepts and ideas related to SQL Server that every database professional should be familiar with.
Relational Data Base Management Systems (RDBMS)
RDBMS stands for Relational Data Base Management Systems. These systems are designed to maintain data records and indices in tables. In a relational database, relationships between data items are expressed through tables, allowing for a high degree of data independence. RDBMSs provide powerful tools for data usage by allowing the recombination of data items from different files.
Properties of Relational Tables
Relational tables have six key properties:
- Values are atomic.
- Column values are of the same kind.
- Each row is unique.
- The sequence of columns is insignificant.
- The sequence of rows is insignificant.
- Each column must have a unique name.
Normalization
Normalization is a data design and organization process applied to data structures in relational databases. The goal of normalization is to minimize redundancy by dividing a database into two or more tables and defining relationships between them. This allows for efficient management of additions, deletions, and modifications of data.
De-normalization
De-normalization is the process of adding redundant data to a database in order to optimize performance. It is sometimes necessary when DBMSs implement the relational model poorly. De-normalization involves moving from higher to lower normal forms of database modeling to speed up database access.
ACID Property
ACID is an acronym for Atomicity, Consistency, Isolation, and Durability. These are essential attributes that database professionals look for when evaluating databases and application architectures. Atomicity ensures that a transaction is an all-or-none proposition. Consistency guarantees that a transaction never leaves the database in a half-finished state. Isolation keeps transactions separated until they are finished, and durability ensures that the database can recover from an abnormal termination.
Normalization Forms
Normalization forms provide guidelines for organizing data in a relational database. Here are some of the commonly used normalization forms:
- 1NF: Eliminate Repeating Groups
- 2NF: Eliminate Redundant Data
- 3NF: Eliminate Columns Not Dependent On Key
- BCNF: Boyce-Codd Normal Form
- 4NF: Isolate Independent Multiple Relationships
- 5NF: Isolate Semantically Related Multiple Relationships
- ONF: Optimal Normal Form
- DKNF: Domain-Key Normal Form
Remember, these normalization guidelines are cumulative. For a database to be in 3NF, it must first fulfill all the criteria of a 2NF and 1NF database.
We hope this post has provided you with a better understanding of some important concepts and ideas related to SQL Server. Stay tuned for more articles in our SQL Server series!