TweetFollow Us on Twitter

MySQL, Part Deux

Volume Number: 21 (2005)
Issue Number: 4
Column Tag: Programming

Getting Started

by Dave Mark

MySQL, Part Deux

In last month's column, I walked you through the process of installing and securing MySQL on your own Mac. Having PHP and MySQL installed on your local machine is a great way to learn about these two important technologies. You can build databases and script them via PHP without a net connection, and without having to wait for files to FTP each time you make a change. If you haven't already done so, go back and review the PHP and MySQL installation columns and make sure they are both up and running.

    If you are new to this column (I know we've had a bunch of new subscribers lately), go to http://www.php.com and http://www.mysql.com and go through the installation process. First install PHP, then install MySQL. If you find the instructions on those sites a bit daunting, there are a number of tutorials for each. Use google. They're pretty easy to find.

Set Up a MySQL Alias

Before we start playing with MySQL, you'll want to set up an alias, so your Unix shell knows how to find the installed mysql executable. For those of you relatively new to Unix, an alias is a shorthand way of referring to a longer command. Here's an example that I find useful. I frequently use the Unix "find" command to locate files on my hard drive. Here's a typical find command:

find . -name "*.mp3"

This command searches the current directory (".") for any files having a name that ends with ".mp3". Try this command yourself. Launch the Terminal application (you'll find it in the Utilities subfolder). When your Terminal window appears, type the command above. Obviously, your results will depend on how many mp3 files you have in the current directory.

Now type this command:

echo $SHELL

This command tells you what shell you are running. Chances are very good that you are running the bash shell (Bourne Again SHell), and the command will return this result:

/bin/bash

If you are using a different shell, try following along anyway. Worst case, you'll just have to use the long form to launch mysql. I'll show you how to do that in a bit.

Assuming you do have a compatible shell, try typing this command:

alias

This command lists your current aliases. If you've never set up any aliases, when you hit return, you'll just get your prompt back.

Now let's set up an alias for the find command. Type this command:

alias fnd='find . -name'

You've just created an alias. Every time you type fnd, the shell will substitute the string "find . -name". To check this, type the command:

alias

The shell should list your new alias:

alias fnd='find . -name'

To test your new alias, type this command:

fnd "*.mp3"

This command should behave exactly the same as your original find command. Cool, you've just created your first alias!

The alias we just created is temporary and will disappear as soon as we logout by closing the window or quitting Terminal. Rather than having to redo all your aliases each time you login or start a new Terminal session, there is a more permanent solution. Each time you login, the bash shell looks for a file in your home directory named .profile and executes, as shell commands, each line in the file.

Take some time to learn either vi or emacs, the two better-known Unix text editors, then edit your .profile and append any alias commands you'd like to have. At the very least, add this alias to your profile:

alias mysql='/usr/local/mysql/bin/mysql'

Note that when you add an alias to your .profile, the alias command won't be executed until you log out and log back in again or close your Terminal window and open a new one. One nice way to re-run your .profile is to use this command:

source .profile

Here's what happened when I ran this command, then ran the alias command to check my current list of aliases:

Dave-Marks-Computer:~ davemark$ alias
alias fnd='find / -name'
Dave-Marks-Computer:~ davemark$ source .profile
Dave-Marks-Computer:~ davemark$ alias
alias fnd='find / -name'
alias mysql='/usr/local/mysql/bin/mysql'

The first alias command only found my fnd alias. I then ran .profile and checked my aliases again and, lo and behold, my new mysql alias was added to the list. Cool!

Another command worth noting is the unalias command. For example:

Dave-Marks-Computer:~ davemark$ unalias fnd
Dave-Marks-Computer:~ davemark$ alias
alias mysql='/usr/local/mysql/bin/mysql'

I used unalias to remove the fnd alias from the list. Of course, since I added that alias to my .profile, as soon as I log back in, the alias will be back.

    Want to learn more about the bash shell? Check out Learning the bash Shell by Cameron Newham & Bill Rosenblatt from our friends at O'Reilly. They just released a 3rd Edition of the book and it looks great. It'll walk you through things like command history, command-line editing, command completion, shell programming, flow control, signal handling, etc. Lots of great stuff, very accessible.

Getting Started with MySQL

With your new, mysql, alias in place, we're ready to launch the MySQL monitor and play a bit. Start by launching mysql:

mysql -u root -p

This command executes the mysql program located in /usr/local/mysql/bin/ (take another look at the alias to see where this path came from). It starts mysql logging in as the user root and tells mysql to prompt you for a password. As a reminder, in last month's column, we added a password to the root account for obvious security reasons. Remember, MySQL maintains its own list of users. The MySQL root is not the same as your computer's root account. They just share the same name.

Here's what I saw when I started mysql:

Dave-Marks-Computer:~ davemark$ mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3 to server version: 4.1.8-standard

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql>

Building a Database and Table

Our first step is to create a database. We'll then populate the database with tables. Each table will have rows and columns and is where the actual data resides.

Our database will be called pets. Within pets, we'll create a table called dogs. As you might imagine, we could also create a table called cats and another table called fish.

Let's start by asking mysql to tell us what databases already exist:

mysql> show databases;
+----------+
| Database |
+----------+
| mysql    |
| test     |
+----------+
2 rows in set (0.07 sec)

mysql>

MySQL ships with two databases. The mysql database contains all the user access privileges. You won't add to that database. The test database is for you to play with. After you finish with this column, go ahead and add your own tables to it. For now, we're going to create a new database called pets. Start by typing this command:

mysql> create database pets
    ->

Hmmm...Notice that mysql did not process your command. Instead, it prompted you with a -> prompt. That's because mysql expects you to end each command with a semicolon (;). One of the nice things about this approach is that you can break complex commands across multiple lines. When you are ready to terminate the command, end the line with a semi.

To finish the previous command, just type a semicolon and mysql will create your pets database:

mysql> create database pets
    -> ;
Query OK, 1 row affected (0.39 sec)

mysql>

Now let's check to see if the database was actually created:

mysql> show databases;
+----------+
| Database |
+----------+
| mysql    |
| pets     |
| test     |
+----------+
3 rows in set (0.63 sec)

mysql>

Note that splitting the command over three lines would work equally well:

mysql> show
    -> databases
    -> ;
+----------+
| Database |
+----------+
| mysql    |
| pets     |
| test     |
+----------+
3 rows in set (0.00 sec)

mysql>

Cool! So now we have a pets database. Before we add a table to the database, let's see what tables already exist:

mysql> show tables;
ERROR 1046 (3D000): No database selected
mysql>

The problem here is that we haven't told mysql which database to look in. Try this command:

mysql> show tables from pets;
Empty set (0.00 sec)

mysql>

That's better. As you can see, the pets database does not yet contain any tables. Rather than have to specify a database with every command that refers to a table, we can issue this command:

mysql> use pets;

Reading table information for completion of table and column names

You can turn off this feature to get a quicker startup with -A

Database changed
mysql>

From now on, when we refer to a table name or issue a table command, mysql will assume we are using the pets database.

Let's create a dogs table:

mysql> create table dogs( 
    -> breed varchar(60),
    -> age int(2),  
    -> dogID int(10) auto_increment primary key );
Query OK, 0 rows affected (0.39 sec)

mysql>

Tables have columns and rows. Each column represents a specific type of data you want stored in your table. You can think of the table definition as a sort of struct definition, with each field as a column header and each row as a specific instance of a struct with all the fields filled in. Our create table command defined the table as having 3 columns. The first column contains a 60 character string. The second character contains a 2-byte integer.

The third column contains a 10-byte integer that will act as the primary key to our database. You'll use this key to do lookups. We'll do that a bit later on in the column. The auto_increment tag tells mysql to assign the next higher number each time a new row is created in the table. This technique works as long as the row is added with this field set to 0. So the first dog added to the table will automatically get a dogID of 1. The next one will get a dogID of 2. And so on. As long as the row is created with a dogID of 0, the dogID field will be filled with the next available dogID.

Let's create a dog:

mysql> insert into dogs values ('poodle', 8, 0 );
Query OK, 1 row affected (0.37 sec)

mysql>

This dog will have a breed of 'poodle', an age of 8, and will get assigned a dogID of 1. Let's verify that:

mysql> select * from dogs;
+-------- +------ +------ +
| breed   | age   | dogID |
+-------- +------ +------ +
| poodle  |   8   |   1   |
+-------- +------ +------ +
1 row in set (0.33 sec)

mysql>

The select command let's you retrieve data from the table. The * is a wildcard, allowing us to retrieve all the rows in the table. Since we've only created a single row, we only get back a single row. Makes sense.

Let's add a second row to the table:

mysql> insert into dogs values ('spaniel',7,0);
Query OK, 1 row affected (0.33 sec)

mysql>

Again, we used 0 as the third argument so we benefit from the auto_increment. Let's take a look at all the rows in our table now that we've added a second row:

mysql> select * from dogs;
+-------- +------ +------ +
| breed   | age   | dogID |
+-------- +------ +------ +
| poodle  |   8   |   1   |
| spaniel |   7   |   2   |
+-------- +------ +------ +
2 rows in set (0.36 sec)

mysql>

Makes sense, right? This variation of select retrieves the data, but orders it by age:

mysql> select * from dogs order by age asc;     
+-------- +------ +------ +
| breed   |  age  | dogID |
+-------- +------ +------ +
| spaniel |   7   |   2   |
| poodle  |   8   |   1   |
+-------- +------ +------ +
2 rows in set (0.00 sec)

mysql>

The asc in the command above stands for ascending. We could have used desc if we wanted the data in descending order.

Now let's change our table data by using the update command. Before you read on, take a look at this command and see if you can figure out what it will do:

mysql> update dogs set breed='mutt' where dogID=1;
Query OK, 1 row affected (0.39 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql>

Got it? Take a look:

mysql> select * from dogs;
+-------- +------ +------ +
| breed   |  age  | dogID |
+-------- +------ +------ +
| mutt    |   8   |   1   |
| spaniel |   7   |   2   |
+-------- +------ +------ +
2 rows in set (0.01 sec)

mysql>

The update command set the breed field to the value of 'mutt' in the row with a dogID of 1. So we changed our poodle into a mutt. Cool!

Now, let's delete the spaniel:

mysql> delete from dogs where dogID=2;
Query OK, 1 row affected (0.33 sec)

mysql>

This delete command will delete all rows from the dogs table with a dogID of 2. Of course, there's only one row that fits that description. Here's the results:

mysql> select * from dogs;
+------ +------ +------ +
| breed |  age  | dogID |
+------ +------ +------ +
| mutt  |   8   |   1   |
+------ +------ +------ +
1 row in set (0.00 sec)

mysql>

As you can see, we're down to just the one row.

Here's a slightly more complex select command:

mysql> select * from dogs where age>4 AND dogID <20;
+------ +------ +------ +
| breed |  age  | dogID |
+------ +------ +------ +
| mutt  |   8   |   1   |
+------ +------ +------ +
1 row in set (0.34 sec)

mysql>

Reading the Documentation

Before we close, here are a few links to help you find your way through the official MySQL web site and documentation. For starters, you'll want to explore the top level at:

http://www.mysql.com

Now, click on the Developer Zone tab and spend a bit of time on this page. Once you have your sea legs, click on the Documentation sub-tab on the Developer Zone page. Here's the direct link:

http://dev.mysql.com/doc/

There are a number of important links on this page (See Figure 1). The second link is a link to a hyperlinked, online version of the MySQL documentation. This link is followed by various links that allow you to download the entire set of documentation to your hard drive. Start by exploring the second link, see if this form of documentation works for you. If not, download the form that works best for you.


Figure 1. The MySQL Reference Manual links

Assuming you've already installed MySQL and followed along with this column, a great place to start reading is this page:

http://dev.mysql.com/doc/mysql/en/tutorial.html

You should recognize a lot of the commands at this point and, hopefully, this column will have filled in enough of the picture so the stuff you haven't yet seen will make sense.

Until Next Month...

Try playing around with the dog table yourself. Add a bunch of rows, make the table more complex. In next month's column, we're going to use PHP to access a MySQL database and table from a web page. Using the mysql monitor is an excellent way to create your tables in the first place, and an excellent tool to check on and repair any data that gets a little futzy. But the real cool stuff happens when you mix MySQL and PHP. Fun, fun, fun!

Oh, and be sure to take a look at Ben Waldie's new Automator book on http://spiderworks.com. It totally rocks. Go, Ben!


Dave Mark is a long-time Mac developer and author and has written a number of books on Macintosh development. Dave has been writing for MacTech since its birth! Be sure to check out the new Learn C on the Macintosh, Mac OS X Edition at http://www.spiderworks.com.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Capture One 11.0.1.40 - RAW workflow sof...
Capture One is a professional RAW converter offering you ultimate image quality with accurate colors and incredible detail from more than 400 high-end cameras -- straight out of the box. It offers... Read more
GraphicConverter 10.5.4 - $39.95
GraphicConverter is an all-purpose image-editing program that can import 200 different graphic-based formats, edit the image, and export it to any of 80 available file formats. The high-end editing... Read more
Dash 4.1.3 - Instant search and offline...
Dash is an API documentation browser and code snippet manager. Dash helps you store snippets of code, as well as instantly search and browse documentation for almost any API you might use (for a full... Read more
Microsoft OneNote 16.9 - Free digital no...
OneNote is your very own digital notebook. With OneNote, you can capture that flash of genius, that moment of inspiration, or that list of errands that's too important to forget. Whether you're at... Read more
DEVONthink Pro 2.9.17 - Knowledge base,...
Save 10% with our exclusive coupon code: MACUPDATE10 DEVONthink Pro is your essential assistant for today's world, where almost everything is digital. From shopping receipts to important research... Read more
OmniGraffle 7.6 - Create diagrams, flow...
OmniGraffle helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use Graffle to... Read more
iFinance 4.3.7 - Comprehensively manage...
iFinance allows you to keep track of your income and spending -- from your lunchbreak coffee to your new car -- in the most convenient and fastest way. Clearly arranged transaction lists of all your... Read more
Opera 50.0.2762.58 - High-performance We...
Opera is a fast and secure browser trusted by millions of users. With the intuitive interface, Speed Dial and visual bookmarks for organizing favorite sites, news feature with fresh, relevant content... Read more
Microsoft Office 2016 16.9 - Popular pro...
Microsoft Office 2016 - Unmistakably Office, designed for Mac. The new versions of Word, Excel, PowerPoint, Outlook and OneNote provide the best of both worlds for Mac users - the familiar Office... Read more
SoftRAID 5.6.4 - High-quality RAID manag...
SoftRAID allows you to create and manage disk arrays to increase performance and reliability. SoftRAID allows the user to create and manage RAID 4 and 5 volumes, RAID 1+0, and RAID 1 (Mirror) and... Read more

Latest Forum Discussions

See All

Around the Empire: What have you missed...
Around this time every week we're going to have a look at the comings and goings on the other sites in Steel Media's pocket-gaming empire. We'll round up the very best content you might have missed, so you're always going to be up to date with the... | Read more »
The 7 best games that came out for iPhon...
Well, it's that time of the week. You know what I mean. You know exactly what I mean. It's the time of the week when we take a look at the best games that have landed on the App Store over the past seven days. And there are some real doozies here... | Read more »
Popular MMO Strategy game Lords Mobile i...
Delve into the crowded halls of the Play Store and you’ll find mobile fantasy strategy MMOs-a-plenty. One that’s kicking off the new year in style however is IGG’s Lords Mobile, which has beaten out the fierce competition to receive Google Play’s... | Read more »
Blocky Racing is a funky and fresh new k...
Blocky Racing has zoomed onto the App Store and Google Play this week, bringing with it plenty of classic kart racing shenanigans that will take you straight back to your childhood. If you’ve found yourself hooked on games like Mario Kart or Crash... | Read more »
Cytus II (Games)
Cytus II 1.0.1 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.1 (iTunes) Description: "Cytus II" is a music rhythm game created by Rayark Games. It's our fourth rhythm game title, following the footsteps of three... | Read more »
JYDGE (Games)
JYDGE 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: Build your JYDGE. Enter Edenbyrg. Get out alive. JYDGE is a lawful but awful roguehate top-down shooter where you get to build your... | Read more »
Tako Bubble guide - Tips and Tricks to S...
Tako Bubble is a pretty simple and fun puzzler, but the game can get downright devious with its puzzle design. If you insist on not paying for the game and want to manage your lives appropriately, check out these tips so you can avoid getting... | Read more »
Everything about Hero Academy 2 - The co...
It's fair to say we've spent a good deal of time on Hero Academy 2. So much so, that we think we're probably in a really good place to give you some advice about how to get the most out of the game. And in this guide, that's exactly what you're... | Read more »
Everything about Hero Academy 2: Part 3...
In the third part of our Hero Academy 2 guide we're going to take a look at the different modes you can play in the game. We'll explain what you need to do in each of them, and tell you why it's important that you do. [Read more] | Read more »
Everything about Hero Academy 2: Part 2...
In this second part of our guide to Hero Academy 2, we're going to have a look at the different card types that you're going to be using in the game. We'll split them up into different sections too, to make sure you're getting the most information... | Read more »

Price Scanner via MacPrices.net

Deals on clearance 15″ Apple MacBook Pros wit...
B&H Photo has clearance 2016 15″ MacBook Pros available for up to $800 off original MSRP. Shipping is free, and B&H charges NY & NJ sales tax only: – 15″ 2.7GHz Touch Bar MacBook Pro... Read more
Apple restocked Certified Refurbished 13″ Mac...
Apple has restocked a full line of Certified Refurbished 2017 13″ MacBook Airs starting at $849. An Apple one-year warranty is included with each MacBook, and shipping is free: – 13″ 1.8GHz/8GB/128GB... Read more
How to find the lowest prices on 2017 Apple M...
Apple has Certified Refurbished 13″ and 15″ 2017 MacBook Pros available for $200 to $420 off the cost of new models. Apple’s refurbished prices are the lowest available for each model from any... Read more
The lowest prices anywhere on Apple 12″ MacBo...
Apple has Certified Refurbished 2017 12″ Retina MacBooks available for $200-$240 off the cost of new models. Apple will include a standard one-year warranty with each MacBook, and shipping is free.... Read more
Apple now offering a full line of Certified R...
Apple is now offering Certified Refurbished 2017 10″ and 12″ iPad Pros for $100-$190 off MSRP, depending on the model. An Apple one-year warranty is included with each model, and shipping is free: –... Read more
27″ iMacs on sale for $100-$130 off MSRP, pay...
B&H Photo has 27″ iMacs on sale for $100-$130 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 27″ 3.8GHz iMac (MNED2LL/A): $2199 $100 off MSRP – 27″ 3.... Read more
2.8GHz Mac mini on sale for $899, $100 off MS...
B&H Photo has the 2.8GHz Mac mini (model number MGEQ2LL/A) on sale for $899 including free shipping plus NY & NJ sales tax only. Their price is $100 off MSRP. Read more
Apple offers Certified Refurbished iPad minis...
Apple has Certified Refurbished 128GB iPad minis available today for $339 including free shipping. Apple’s standard one-year warranty is included. Their price is $60 off MSRP. Read more
Amazon offers 13″ 256GB MacBook Air for $1049...
Amazon has the 13″ 1.8GHz/256B #Apple #MacBook Air on sale today for $150 off MSRP including free shipping: – 13″ 1.8GHz/256GB MacBook Air (MQD42LL/A): $1049.99, $150 off MSRP Read more
9.7-inch 2017 WiFi iPads on sale starting at...
B&H Photo has 9.7″ 2017 WiFi #Apple #iPads on sale for $30 off MSRP for a limited time. Shipping is free, and pay sales tax in NY & NJ only: – 32GB iPad WiFi: $299, $30 off – 128GB iPad WiFi... Read more

Jobs Board

*Apple* Data Center Site Selection and Strat...
# Apple Data Center Site Selection and Strategy Research Analyst Job Number: 83708609 Santa Clara Valley, California, United States Posted: 18-Jan-2018 Weekly Hours: Read more
Security Engineering Coordinator, *Apple* R...
# Security Engineering Coordinator, Apple Retail Job Number: 113237456 Santa Clara Valley, California, United States Posted: 18-Jan-2018 Weekly Hours: 40.00 **Job Read more
Firmware Engineer - *Apple* Accessories - A...
# Firmware Engineer - Apple Accessories Job Number: 113422485 Santa Clara Valley, California, United States Posted: 18-Jan-2018 Weekly Hours: 40.00 **Job Summary** Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Store Leader - Retail District Manag...
Job Description:Job SummaryAs more and more people discover Apple , they visit our retail stores seeking ways to incorporate our products into their lives. It's your Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.