Database Reference
In-Depth Information
2. What is Access control?
3. Write a short note on Transaction Processing.
4. Explain types of Locking.
5. What the function of Grant and revoke statement.
Chapter 7
7.1 Introduction to SQL
SQL, pronounced “sequel,” is an acronym for Structured Query Language. A standards
body called ANSI, the American National Standards Institute, maintains this language.
SQL is a powerful query language that was created as a means to communicate with data-
bases. Databases store data. SQL can be used to view, manipulate, and create this data.
It can even define the structures that will hold the data. Because SQL is a standards-con-
trolled language, it is reusable from database to database.
What are the advantages of SQL?
1. SQL is not a proprietary language used by specific database vendors. Almost
every major DBMS supports SQL, so learning this one language will enable you
to interact with just about every database you'll run into.
2. SQL is easy to learn. The statements are all made up of descriptive English words,
and there aren't that many of them.
3. Despite its apparent simplicity, SQL is actually a very powerful language, and
by cleverly using its language elements you can perform very complex and
sophisticated database operations.
7.2 SQL Tools
Oracle has provided a user-friendly interactive tool for running SQL since its first release.
The SQL*Plus tool today has four variations from which to choose:
SQL*Plus Command Line. Use this when you don't have a Windows interface, such as
when using telnet to reach a remote UNIX database server.
SQL*Plus Windows. Use this in a Windows-capable environment (can be invoked using a
network name from a client or directly on the database server, regardless of the operating
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