|MS SQL Server Administration: Database Concepts
Physical Database Design
Understanding the Design concepts are very essential for a person engaged in the administration of MS SQL Server. There are two kinds of database designs, viz. physical and logical. Things like files and file groups are included in the physical design of a database. Most efficient ways of storing and accessing data is the objective of the physical design.
Logical Database Design
Objects like tables and their inter-relationship constitute the logical design of a database. The logical design is not aware and also independent of any specific Database Management System (DBMS). Modeling a real-world data scenario is its only concern. For example, for creation of a database in both SQL Server and Access, by using the same logical design, one can come up with exactly the same database so far as the logical design is concerned. However in respect of physical design, there can be very different physical designs for the two databases. Only one file would go to make the Access database in contrast to which there would be many different files spread over many hard drives for making up the SQL Server database.
Physical/Logical Implementation of Database
One important point to remember is that the two concepts, viz. the physical implementation of a database and the logical implementation of a database are two completely different concepts. They are independent of each other for most of the parts. Another example can be cited where a database is located on the SQL Server and it gets added to it another data file. In this case the logical design would remain unchanged although with the addition of the other file, the physical design of the database has changed. This highlights the distinctness between the two concepts. Databases mostly worked with are relational databases. This is so because SQL Server is a Relational Database Management System (RDBMS). Designing of a relational database is therefore very important.