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