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Introduction to Databases for Web Developers
The Data Dictionary  
How does the database know where all of these tables are located? Well, behind the scenes, the database maintains a "data dictionary" (a.k.a. catalog) which contains a list of all the tables in the database as well as pointers to their locations.

Essentially, the data dictionary is a table of tables containing a list of all the tables in the database, as well as the structure of the tables and often, special information about the database itself.

When you use SQL to talk to the database and provide a table name, the database looks up the table you referred to in the data dictionary. Of course, you needn't worry about the data dictionary; the database does all the searching itself. As we said before, you just need to know the name of the table you want to look at.

It is interesting to note that because the data dictionary is a table, in many databases, you can even query the data dictionary itself to get information about your environment. This can often be a very useful tool when exploring a new database.

Okay, so how do you actually grab table data using the data dictionary? Well, in an SQL database you create "views". Let's examine views a bit.

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