MySQL Basics for Visual Learners PHẦN 4 pdf

Type: SELECT id, first, last FROM name ►► ORDER BY id; The window should look like this: In this query, ORDER BY id places the records in numeric order, based on their id numbers.. GE

GETTING STARTED WITH MYSQL

38

3 Type:

SELECT id, first, last FROM name ►►

ORDER BY id;

The window should look like this:

In this query, ORDER BY id places the records in numeric order, based on their id numbers

Tip: To arrange records in reverse numeric or reverse

alphabetical order, add DESC on the end For instance, type:

SELECT first, last FROM name ORDER BY last

DESC;

The DESC option refers to the word “descending.” It tells MySQL

to order things descending from high to low instead of the default: low to high

GETTING STARTED WITH MYSQL 39

4 Type:

\q;

then press ENTER

This closes your MySQL database connection

You are now logged out of the MySQL server: the mysql> prompt is gone

GETTING STARTED WITH MYSQL

40

5 Type:

exit then press ENTER

The Konsole window should close

GETTING STARTED WITH MYSQL 41

Giving MySQL commands to a Web server

MySQL’s client/server arrangement makes it well-suited to Web applications With MySQL server running on a Web server, you can use a MySQL client to update/add/delete data remotely

This book assumes that you’ve installed MySQL on your desktop Linux computer Both the MySQL client and server programs are

on this computer, called localhost

To give commands to a MySQL server program running on a Linux Web server, just replace localhost with the IP address

of the Web server, such as 10.0.1.10

or the domain name of the Web server, such as mysql.domain.com

Provided you have an Internet connection with the Web server, and the proper username/password to access it, your commands will work

GETTING STARTED WITH MYSQL

42

ADMINISTERING DATABASES 43

Administering

Databases

In this section, you’ll learn how to:

• Restart MySQL

• Back up a database

• Delete a table

• Delete a database

• Restore a database

ADMINISTERING DATABASES

44

Restart MySQL

If you’ve shut off your computer since the last exercise, you might need to restart MySQL

First, login to your Linux computer as the Root user Then restart the MySQL server:

1 Open the Konsole window and login as the Root user

2 At the prompt, type:

/etc/rc.d/init.d/mysql start

then press ENTER

3 Type:

exit then press ENTER

You’re now logged out of the Linux Root account

ADMINISTERING DATABASES 45

Now you’ll have to establish a MySQL client connection to the MySQL server:

4 At the $ prompt, type:

mysql –u root –p

then press ENTER

5 Type the password used to gain root access to the MySQL

server:

textbook

then press ENTER

ADMINISTERING DATABASES

46

The window should look like this:

ADMINISTERING DATABASES 47

Back up a database

1 Make sure the Konsole window is open If it’s not, open it

2 Make sure you’re logged out of the MySQL server

Tip: Give the \q; command

3 At the[yourusername@localhost yourusername]$

prompt, type:

pwd

then press ENTER

The window should look something like this:

ADMINISTERING DATABASES

48

The Linux command pwd is an acronym for print working directory In other words, “print the path to the directory I’m working in.”

When you first open the Konsole window, Linux automatically goes to your home directory

Each user on a Linux computer has his own home directory, which contains preferences and files unique to that user

ADMINISTERING DATABASES 49

4 Type:

cd / then press ENTER

The window should look something like this:

This Linux command has two parts:

cd tells the computer to change directory

/ takes you to the root directory

ADMINISTERING DATABASES

50

Root directory at the top

Starting from the Root directory, you can dig down into all the other directories, or folders, on the computer

ADMINISTERING DATABASES 51

5 Type:

pwd then press ENTER

The window should look something like this:

This is the path to your current working directory on this computer: root

6 Type:

cd then press ENTER

The cd command takes you to your home directory

ADMINISTERING DATABASES

52

7 Type:

pwd then press ENTER

You should now be back where you started, in your home directory:

8 Type:

mkdir backups then press ENTER

mkdir is a Linux command to create a new directory, in this case a new directory within your home directory called backups

9 Type:

ls then press ENTER

The ls command lists all the items in the current directory: the backups, Desktop, Documents, and tmp directories