Table of Contents
- 4.1 Creating and Selecting a Database
- 4.2 Creating a Table
- 4.3 Loading Data into a Table
- 4.4 Retrieving Information from a Table
Once you know how to enter SQL statements, you are ready to access a database.
Suppose that you have several pets in your home (your menagerie) and you would like to keep track of various types of information about them. You can do so by creating tables to hold your data and loading them with the desired information. Then you can answer different sorts of questions about your animals by retrieving data from the tables. This section shows you how to perform the following operations:
Create a database
Create a table
Load data into the table
Retrieve data from the table in various ways
Use multiple tables
The menagerie database is simple (deliberately), but it is not difficult to think of real-world situations in which a similar type of database might be used. For example, a database like this could be used by a farmer to keep track of livestock, or by a veterinarian to keep track of patient records. A menagerie distribution containing some of the queries and sample data used in the following sections can be obtained from the MySQL website. It is available in both compressed tar file and Zip formats at https://dev.mysql.com/doc/.
SHOW statement to find out
what databases currently exist on the server:
mysql> SHOW DATABASES; +----------+ | Database | +----------+ | mysql | | test | | tmp | +----------+
mysql database describes user access
test database often is
available as a workspace for users to try things out.
The list of databases displayed by the statement may be different
on your machine;
does not show databases that you have no privileges for if you do
not have the
privilege. See SHOW DATABASES Statement.
test database exists, try to access it:
mysql> USE test Database changed
does not require a semicolon. (You can terminate such statements
with a semicolon if you like; it does no harm.) The
USE statement is special in another
way, too: it must be given on a single line.
You can use the
test database (if you have
access to it) for the examples that follow, but anything you
create in that database can be removed by anyone else with access
to it. For this reason, you should probably ask your MySQL
administrator for permission to use a database of your own.
Suppose that you want to call yours
The administrator needs to execute a statement like this:
mysql> GRANT ALL ON menagerie.* TO 'your_mysql_name'@'your_client_host';
your_mysql_name is the MySQL user name
assigned to you and
your_client_host is the
host from which you connect to the server.