Chapter 2. The SQL Language

Table of Contents
2.1. Introduction
2.2. Concepts
2.3. Creating a New Table
2.4. Populating a Table With Rows
2.5. Querying a Table
2.6. Joins Between Tables
2.7. Aggregate Functions
2.8. Updates
2.9. Deletions

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 Understanding the New SQL and A Guide to the SQL Standard. 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 started psql.

Examples in this manual can also be found in the PostgreSQL source distribution in the directory src/tutorial/. 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. (You must use GNU make for this — it may be named something different on your system, often gmake.) Then, to start the tutorial, do the following:

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

mydb=> \i basics.sql

The \i command reads in commands from the specified file. The -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.