Welcome to our blog series on SQL Server concepts and ideas! In this post, we will discuss some fundamental concepts that every SQL Server developer should be familiar with: OLTP, OLAP, and normalization.

OLTP and OLAP

OLTP stands for On-Line Transaction Processing. It refers to a system that is designed to handle a large number of concurrent users and modify data at the moment it is received. OLTP systems are used for fundamental business tasks and typically involve simple, quick-running queries.

On the other hand, OLAP stands for Online Analytical Processing. It is an application that collects, manages, processes, and presents multidimensional data for analysis and management purposes. OLAP systems are used for planning and decision making and often involve complex, long-running queries.

The main difference between OLTP and OLAP lies in their data sources, process goals, queries and process scripts, and database design. OLTP systems use operational data from the original data source, while OLAP systems consolidate data from various sources. OLTP focuses on business processes, while OLAP provides multi-dimensional views of business activities. Queries in OLTP are simple and quick, while OLAP queries are complex and long-running. In terms of database design, OLTP systems use a normalized small database, while OLAP systems use a denormalized large database.

Normalization Forms

Normalization is a process of organizing data in a database to eliminate redundancy and improve data integrity. There are different normalization forms, each with its own set of rules. Here are some of the most commonly used normalization forms:

• 1NF (First Normal Form): Eliminate repeating groups and make a separate table for each set of related attributes.
• 2NF (Second Normal Form): Eliminate redundant data by removing attributes that depend on only part of a multi-valued key.
• 3NF (Third Normal Form): Eliminate columns not dependent on the key by removing them to a separate table.
• BCNF (Boyce-Codd Normal Form): Separate non-trivial dependencies between candidate key attributes into distinct tables.
• 4NF (Fourth Normal Form): Isolate independent multiple relationships by ensuring that no table contains two or more 1:n or n:m relationships that are not directly related.
• 5NF (Fifth Normal Form): Isolate semantically related multiple relationships based on practical constraints.
• ONF (Optimal Normal Form): A model limited to only simple facts, expressed in Object Role Model notation.
• DKNF (Domain-Key Normal Form): A model free from all modification anomalies.

It’s important to note that these normalization forms are cumulative. For a database to be in 3NF, it must first fulfill all the criteria of a 2NF and 1NF database.

Operational Data Store (ODS) and ER Diagram

An Operational Data Store (ODS) is a database structure that serves as a repository for near real-time operational data. It is different from a traditional data warehouse, as it focuses on storing data for operational systems rather than long-term trend analysis. The ODS can also become the enterprise-shared operational database, allowing re-engineered operational systems to use it as their main database.

An Entity Relationship (ER) Diagram is a data modeling tool that helps organize data into entities and define the relationships between them. It is a specialized graphic that illustrates the interrelationships between entities in a database. ER diagrams are commonly used in relational databases to show the structure of each table and the links between tables.

Understanding these concepts is crucial for anyone working with SQL Server. Whether you are a developer, database administrator, or data analyst, having a solid understanding of OLTP, OLAP, normalization, ODS, and ER diagrams will greatly enhance your ability to design and optimize SQL Server databases.

Stay tuned for more articles in our SQL Server Concepts and Ideas series!