## Chapter 2. The SQL Language

## 2.1. Introduction

This chapter provides an overview of how to use SQL to perform simple operations. This tutorial is only intended to give you an introduction and is in no way a complete tutorial on SQL. Numerous books have been written on SQL, including [melt93] and [date97]. You should be aware that some PostgreSQL language features are extensions to the standard.

In the examples that follow, we assume that you have created a database named `mydb`, as described in the previous chapter, and have been able to start psql.

Examples in this manual can also be found in the PostgreSQL source distribution in the directory `src/tutorial/`. (Binary distributions of PostgreSQL might not compile these files.) To use those files, first change to that directory and run make:

    $ cd ..../src/tutorial
    $ make

This creates the scripts and compiles the C files containing user-defined functions and types. Then, to start the tutorial, do the following:

    $ cd ..../tutorial
    $ psql -s mydb

    ...

    mydb=> \i basics.sql

The `\i` command reads in commands from the specified file. `psql`'s `-s` option puts you in single step mode which pauses before sending each statement to the server. The commands used in this section are in the file `basics.sql`.