-SQLServer简介外文翻译-其他专业.doc

外文原文 Introduction to SQL Server By Samuel Relational databases have been around for 30 years, but they were not the original kind ofdatabase, nor are they the newest kind of database. XML and object-oriented data structures haveevolved in recent years. But relational databases are still by far the most popular kind of database available and will be for some time to come. SQL is the abbreviation of Structured Query Language and it is for relational databases, as the title indicates this is only for fresher who has just started the carrier or who is waiting to open up the carrier in the application programming side. But that does not mean this article is a tutorial for a fresher who does not know anything about SQL.This article is meant for who already have a little knowledge in SQL and want toimprove it. What Does SQL Do? First, SQL is the premier tool for viewing information from a relational database. It doesn’t just give you a data dump. SQL gives you sophisticated tools to summarize, consolidate, and calculate from the data. Using table relationships, data can be combined from multiple tables in a number of ways. With a properly designed database, SQL can answer practically any question about the data. Second, SQL provides commands to manipulate the data in a relational database. Records can be updated and added to or deleted from a table. Here is SQL as a database language really shines. Procedural programming languages, such as BASIC, might require several lines of code to update a record in a database table. In addition, procedural programming languages would have to use some sort of looping structure to repeat this process on every record. SQL operates on an entire set of records all at the same time. SQL is like haiku for programmers; often a dozen words or fewer can delete or change thousands of records. Finally, SQL is a complete data definition language (DDL). The database itself can be created along with all tables, fields, primary keys, and relationshi