Network Administration: SQL Basics

SQL, which stands for Structured Query Language, is a language designed to extract, organize, and update information in relational databases. Originally, SQL was envisioned as an English-like query language that untrained end users could use to access and update relational database data.

But in reality, SQL is nothing like English, and it’s far too complicated and esoteric for untrained users. But it has become the overwhelming favorite among programmers who develop applications that access relational databases.

SQL dialects

Like most computer languages, SQL has several different dialects. In fact, each major brand of SQL database server has its own dialect of SQL. These dialects are 95 percent the same, so a basic SQL statement is likely to work the same regardless of the database server you use it with. But there are many variations in how the more advanced features of SQL work.

The version of SQL used by Microsoft’s SQL Server is known as T-SQL.

SQL statements

Like other programming languages, SQL uses statements to get its work done.

Common SQL Statements

SQL Statement	What It Does
use	Identifies the name of the database that subsequent SQL statements apply to.
select	Retrieves data from one or more tables. This is the SQL statement that’s used the most.
insert	Inserts one or more rows into a table.
delete	Deletes one or more rows from a table.
update	Updates existing rows in a table.
create	Creates tables and other database objects.
alter	Alters the definition of a table or other database object.
drop	Deletes a table or other database object.

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