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SQL Server Variables

Variable code

Microsoft SQL Server 2012 is a database platform for large-scale online transaction processing (OLTP), data warehousing, and e-commerce applications; it is also a business intelligence platform for data integration, analysis, and reporting solutions.
The code base for MS SQL Server (prior to version 7.0) originated in Sybase SQL Server, and was Microsoft's entry to the enterprise-level database market, competing against Oracle, IBM, and, later, Sybase itself. Microsoft, Sybase and Ashton-Tate originally teamed up to create and market the first version named SQL Server 1.0 for OS/2 (about 1989) which was essentially the same as Sybase SQL Server 3.0 on Unix, VMS, etc. Microsoft SQL Server 4.2 was shipped around 1992 (available bundled with Microsoft OS/2 version 1.3). Later Microsoft SQL Server 4.21 for Windows NT was released at the same time as Windows NT 3.1. Microsoft SQL Server v6.0 was the first version of SQL Server that was architected for NT and did not include any direction from Sybase.

What Makes Up a SQL Server Database?

What makes up a database? Data for sure. (What use is a database that does not store anything?) But a Relational Database Management System (RDBMS) is actually much more than data. Today's advanced RDBMSs not only store your data, they also manage that data for you, restricting the kind of data that can go into the system, and facilitating getting data out of the system. If all you want is to store the data somewhere safe, you could use just about any data storage system. RDBMSs allow you to go beyond the storage of the data into the realm of defining what that data should look like, or the business rules of the data. Do not confuse what I am calling the "business rules of the data" with the more generalized business rules that drive your entire system (for example, preventing someone from seeing anything until they have logged in, or automatically adjusting the current period in an accounting system on the first of the month). Those types of rules can be enforced at virtually any level of the system (these days, it is usually in the middle or client tier of an n-tier system).
Instead, what I am talking about here are the business rules that specifically relate to the data. For example, you cannot have a sales order with a negative amount. With an RDBMS, you can incorporate these rules right into the integrity of the database itself.
The notion of the database taking responsibility for the data within, as well as the best methods to input and extract data from that database, serves as the foundation for this course. This module provides an overview of the rest of the course. Most items discussed in this module are covered again in later modules, but this module is intended to provide you with a road map or plan to bear in mind as you progress through the course. With this in mind, I will give you a high-level look into:
  1. Database objects
  2. Data types
  3. Other database concepts that ensure data integrity