SQL Server 2000, the latest and greatest of the SQL Server platforms, is still a relational database management system (RDBMS). All RDBMSs share some qualities.These features are the basics of what make up any RDBMSs, and include thefollowing:
? As its name implies, the purpose of an RDBMS is to manage relational databases. A relational database is a grouping of tables. The tables are broken down into rows, also known as records, and the records are broken down into columns, also known as fields. Without these, you would have nothing to manage.
? All RDBMSs use SQL, or a variation of it, to manipulate the data contained in any of the databases. SQL (correctly pronounced S-Q-L) was developed at IBM in the late 1970s.
? RDBMSs must maintain data integrity. In other words, every relational database needs to ensure that if data in multiple tables is updated, all the updates take place. For example, imagine a banking system that contains two tables: one for your savings account and one for your checking account. You call your bank and ask to transfer $100 from savings to checking. This process involves subtracting $100 from your savings account and adding $100 to your checking account. If the bank loses power after the $100 is deleted from the table, what happens? If there is no data integrity, you have just lost $100. With data integrity, when the server is powered back on, the RDBMS realizes that the subtraction completed but that the addition didn't,and it cancels the whole transaction.
? Most RDBMSs strive to maintain separation between the actual data and the business logic that ensures that the data in the database is maintained in a constant state. In most cases, you will want to try to limit the amount of business functionality that you maintain in the database server.
? Many RDBMSs store data in such a way that redundant data is eliminated through some of type of compression. That doesn't mean data is lost—rather,it means that less storage space is needed.
? All RDBMSs provide some sort of security for the databases they manage.This security is usually at least a two-level process. First, any user who wants to access the system must identify herself with a valid login and password.When she passes this level of authentication, most systems have rules, called permissions, that block a user from accessing data to which she shouldn't have access.
? As its name implies, the purpose of an RDBMS is to manage relational databases. A relational database is a grouping of tables. The tables are broken down into rows, also known as records, and the records are broken down into columns, also known as fields. Without these, you would have nothing to manage.
? All RDBMSs use SQL, or a variation of it, to manipulate the data contained in any of the databases. SQL (correctly pronounced S-Q-L) was developed at IBM in the late 1970s.
? RDBMSs must maintain data integrity. In other words, every relational database needs to ensure that if data in multiple tables is updated, all the updates take place. For example, imagine a banking system that contains two tables: one for your savings account and one for your checking account. You call your bank and ask to transfer $100 from savings to checking. This process involves subtracting $100 from your savings account and adding $100 to your checking account. If the bank loses power after the $100 is deleted from the table, what happens? If there is no data integrity, you have just lost $100. With data integrity, when the server is powered back on, the RDBMS realizes that the subtraction completed but that the addition didn't,and it cancels the whole transaction.
? Most RDBMSs strive to maintain separation between the actual data and the business logic that ensures that the data in the database is maintained in a constant state. In most cases, you will want to try to limit the amount of business functionality that you maintain in the database server.
? Many RDBMSs store data in such a way that redundant data is eliminated through some of type of compression. That doesn't mean data is lost—rather,it means that less storage space is needed.
? All RDBMSs provide some sort of security for the databases they manage.This security is usually at least a two-level process. First, any user who wants to access the system must identify herself with a valid login and password.When she passes this level of authentication, most systems have rules, called permissions, that block a user from accessing data to which she shouldn't have access.
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