SQL is not just another programming language, it is a database language designed specifically to retrieve and manipulate data.
There is an SQL standard that is generally supported by all the major RDBMS vendors; though one must pay close attention to the dialect used by any particular RDBMS, SQL is nevertheless lingua franca of the database world.
Using SQL, you can create (and destroy) a number of database objects, insert, select, update or delete data.
There are two different types of SQL used in the client applications — embedded SQL and dynamic SQL — and each has its own use.
OLAP is relatively new to SQL. Part of the rapidly evolving field of business intelligence, OLAP facilitates analyzing data for business support information.
XML has emerged as a standard data exchange format, with pledged support by virtually every vendor in the field. Some of the RDBMS products (and all three major RDBMS vendors chosen for this book) are coming up with a native support for XML — an open standard for structuring and describing data. It is becoming the de-facto data exchange standard for the industry, especially over the Internet.