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SQL DROP Index & DROP Database: Tutorial

Instructor: David Gloag

David has over 40 years of industry experience in software development and information technology and a bachelor of computer science

We collect and organize information, lots of it. So it makes sense that we'll want to delete some of it at times. In this lesson, we'll take a look at SQL, indexes, databases, and how the DROP command affects them.

Cleaning House

We collect so much information. At times, it seems like we're drowning in it. Businesses collect it for consumer trending and financial reasons. Governments collect it for taxation and social service reasons. And even we collect it for personal organization or entertainment reasons. Obviously, this is an ever-increasing trend, and it can't continue indefinitely. But what can we do? How can we get a handle on things? The first step is to organize it all, and take stock. The second is to look at throwing away the information we can't use. That is where SQL comes in.

What is SQL?

Structured Query Language (SQL) is a command-oriented language designed to allow someone to interact with a database. By interact, we mean perform activities such as storing, searching, and retrieving information. IBM developed SQL in the early 1970's, but the language didn't become commercially available until Oracle released it in 1979. Since then, many companies have adopted it, both as a tool, and as a component of their product offerings. Because of this, it has become a standard for manipulation and maintenance of databases.

What is a Database?

A database is a collection of information centered on a particular theme. You interact with a number of them each day, although you may be unaware of their presence. Phone numbers stored on your cell phone, the email stored on your personal computer, and the transactions you make through your credit card are all contained in databases.

What is an Index?

An index, put simply, is a sequential set of values that imply an ordering to the elements of a database. We use 'imply' because the ordering indicated by the index will not necessarily match the physical ordering of the information in the database. In fact, most of the time, it won't. Indexes are valuable because we often want to traverse (step through record by record) information without physically reordering it, which is time consuming. As an example, say you wanted to print the records sorted alphabetically by last name. No problem, if you have a last name index. Then, say that you wanted to print the same list, but this time ordered by age. If you have an index, again no problem. But if you didn't, you would have to physically reorder the records.

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