Database types and definitions

This weeks blog task has two parts:

1. What is a database? In our own words, describe what we think a database is.
2. What are the different types of databases? Give examples of the different types of databases.

Wikipedia describes a database as:

A database is an integrated collection of logically related records or files which consolidates records into a common pool of data records that provides data for many applications.

If I was putting this in to my own words, I would describe it as a collection of information that is structured in such a way that any relevant information is easily accessible.

The second question is open to a bit of interpretaion. Many of the answers in the class had things like MySQL, Oracle, Access, SqlServer. According to WikiAnswers, the different types of databases are, "Hierarchical, Network, Relational, Object Relational".

Studying for Chapter 8 test...

One of the questions in the practice test was this one from the True/False section:

• 8. Only six different types of exceptions can occur in a visual basic program.

Now, I don't know about you guys, but I looked, read then re-read the chapter, headbutted the wall (thank God we don't have a cat, for it would surely have been kicked) and yet I still couldn't find a definitive answer to this question.

I know, I know... Page 592 has a table with six exception types in it. But I direct you to the paragraph above the table:

Different types of exceptions can occur. The table shown in figure 8-46 identifies some of the of the possible exceptions.

Does this meant the correct answer is False? The table after all only shows six exceptions and it doesn't say anywhere in the text, "This list is by no means exhaustive or complete" etc. So you could probably make a case for saying that the answer is True if you really wanted to push it.

Anyway, I went searching and found another, larger, yet still by no means exhaustive, list of exceptions. It can be found at http://www.exforsys.com/tutorials/vb.net-2005/vb.net-exceptions.html and succeeds where the book fails, gives us a definitive answer to the question.

And just in case you are wondering... Yes, I am grumpy. Bloody Cats!!! Someone must have swapped their playbook with The Hitchhikers Guide to the Galaxy because it apparently has the words "Don't Panic" written across the front in large, friendly letters. Yeah right, 7 of our best 22 out injured and another 6 of them playing with injuries or just out of form, four weeks from finals... Nah, don't worry about panic, I think we've moved beyond that point. Next stop, despair.

Cats and Dogs Assignment

I discovered a few things while doing my Cats and Dogs assignment. Firstly, you can make one panel the child of another panel without realizing it. I made this mistake as I have four panels that fit in to the space of one panel. When I slid them in to place manually, one of the panels wouldn't show up because it was the child of a different panel which, through the code created had had its visibility set to false. This meant that the program would fail to run properly.

What I had to do to fix this problem was to extend the form and seperate all of the panels. I then set the panels in to position using their Location property and then resized the form back to its original size (i.e, big enough to hold one panel). From this point, the program ran perfectly, showing all the panels at the appropriate times.

Another thing I came across was the use of images. I had them set from an absolute path on my memory stick. The problem was that when I handed the assignment in, Rachael wouldn't have access to the pictures for the slide show. I figured that there had to be a way to set the pictures in to the program itself, but I could not see how to do this. I tried putting the pictures into the Resources folder, but I had dragged and dropped and it didn't work when I tried to use Intellisence. I found a very easy to use example for adding pictures to your resource folder written by Craig Cureton, one of the students in the other Cert IV Programming class and this problem was also solved.

I still have two assignments to get done for Programming, the Class Diagram and the Alarm Clock. I'm hoping to have these done by the end of the week.

Methods used in Now function...

Our blog task this week is to list the methods that can be used in the Now function. Our assessment involved using the Now function, but we used it in a very simple way. So Rachael has given us this task to show what other methods can be used.

If you want to display the time in a label for example, you might use something like this:
lblCurrentTime.Text = Now
This will retrieve the current time and date from the computer and display it in the label lblCurrentTime. If you only want to display the time though, you would need to do it like this:
lblCurrentTime.Text = Now.ToString("HH:mm:ss")
This will display the time in Hours, Minutes and Seconds. It will only show the time when the program starts though, it won't keep updating the time to keep it current. If you want it to act like a clock, you need to add a Timer function and put this code in to the function as well.






I have been posting a little bit on this function in recent times, relating to my sleep calculator. What I'm going to do is use this function to create a real, bonafide sleep calculator, but that will have to wait until the workload of assignments has thinned out a little bit.
Anyway, what other methods can be added to the Now function? So far ToString has been added. According to the list in Intellisense, the following can be added as methods to the Now function:

• Add (AddDays, AddHours, AddMilliseconds, AddMinutes, AddMonths, AddSeconds, AddTicks, AddYears)
• To (ToString, ToLongTimeString, ToOADate, ToShortDateString, ToShortTimeString, ToUniversalTime, ToBinary, ToFileTime, ToFileTimeUtc, ToLocalTime)
• TryParse, TryParseExact
• Compare, CompareTo
• DaysInMonth
• Equals
• From (FromBinary, FromFileTime, FromFileTimeUtc, FromOADate)
• Get (GetDateTimeFormat, GetHashCode, GetType, GetTypeCode)
• IsDaylightSavingTime, IsLeapYear
• Parse, ParseExact
• ReferenceEquals
• SpecifyKind
• Subtract

I spent a couple of hours searching the internet looking for a list like this one. Once I finally used my brain however, I realised that I could find what I needed in Intellisense. I'm not too sure what it is that all of these methods do, but I'm sure we'll be finding out at least some of them in the coming months.

Using your computers date for the sleep calculator

I had someone post a comment the other day asking how the "rather silly sleep calculator" could use the current date according to the computer to make it's calculation. First of all, let me say that I'm scared, I didn't mean to get readers :-). Secondly, it's really cool that any of them take the time to comment let alone read anything I post.

Anyway, I want to point out straight off that my program probably wouldn't work as is with the computers own date. The reason for this is that the program (as I wrote in the original post on the sleep calculator) uses short years and months. You will lose 5 days in a normal year (6 in a leap year), lose 1 day for seven months each year and gain 2 days for one month (except in a leap year when you only gain 1 day for that month). No, to make this workable, a whole new equation will need to be worked out.

Having said all of that, I did some digging and found that you can use the Now() function to use the computers date. I get the distinct impression that this function is for older versions of VB. I can tell you that in Visual Studio, it comes up black.

A reader by the name of Jack posted this comment:

My.Computer.Clock.LocalTime.Year
this is the code that shows the year from your computer system, and you can try the month and the day as the same.

which would make sense (however, it was posted on April 1st local time...), but you would still need to store the result in a variable obviously.

I also found a pretty cool site called Top54u that showed how to display the date in various formats once you've captured it. I'd love to look into this further and redevelop the "rather silly sleep calculator" into an awesome and actually usable sleep calculator. I have the next two weeks off class, so I might give that a shot during the "break" (a term used very loosely as I have HEAPS of work to catch up on in the time).

Anyway, I hope there has been some helpful stuff in here and thanks to everyone who has been reading and keep the comments coming.

All the best,

Tim.

Some missing blog tasks...

It would appear that I have missed some blog tasks over the journey of my course so far. To be honest, I was under the impression that the tasks in question were being given out because some people in the class had expresses a concern that they didn't know what to blog on. I wasn't aware that they were compulsory topics. Nonetheless, they are, so I shall do them now.

We were supposed to list 2 VB resources. I listed the companion site that goes along with the book we use for class. You can find it in the archives if you would like to have a look at it. So I'm going to add 3 more resource sites for good measure:

• http://www.freeprogrammingresources.com/vbtutor.html . This site covers VB from the early days onwards.
• http://www.thevbzone.com/ . This site looks pretty good from what I've seen of it.
• http://www.homeandlearn.co.uk/net/nets11p1.html . This is one that Rachael has listed also, but it comes with some pretty handy information on classes and what not.

ASCII and Unicode
Information on ASCII code was taken straight from the Wikipedia site:

American Standard Code for Information Interchange (ASCII), pronounced /ˈæski/^[1] is a coding standard that can be used for interchanging information, if the information is expressed mainly by the written form of English words. It is implemented as a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communicationscharacter-encoding schemes—which support many more characters than did the original—have a historical basis in ASCII. equipment, and other devices that work with text. Most modern

Historically, ASCII developed from telegraphic codes. Its first commercial use was as a seven-bit teleprinter code promoted by Bell data services. Work on ASCII formally began October 6, 1960, with the first meeting of the American Standards Association's (ASA) X3.2 subcommittee. The first edition of the standard was published in 1963,^[2][3] a major revision in 1967,^[4] and the most recent update in 1986.^[5] Compared to earlier telegraph codes, the proposed Bell code and ASCII were both ordered for more convenient sorting (i.e., alphabetization) of lists, and added features for devices other than teleprinters.

ASCII includes definitions for 128 characters: 33 are non-printing, mostly obsolete control characters that affect how text is processed;^[6] 94 are printable characters, and the space is considered an invisible graphic.^[7] The most commonly used character encoding on the World Wide Web was US-ASCII^[8] until 2008, when it was surpassed by UTF-8.^[9]

For more information, go to http://en.wikipedia.org/wiki/ASCII .

Unicode information was also taken from Wikipedia:

Unicode is a computing industry standard allowing computers to consistently represent and manipulate text expressed in most of the world's writing systems. Developed in tandem with the Universal Character Set standard and published in book form as The Unicode Standard, Unicode consists of a repertoire of more than 100,000 characters, a set of code charts for visual reference, an encoding methodology and set of standard character encodings, an enumeration of character properties such as upper and lower case, a set of reference data computer files, and a number of related items, such as character properties, rules for normalization, decomposition, collation, rendering and bidirectional display order (for the correct display of text containing both right-to-left scripts, such as Arabic or Hebrew, and left-to-right scripts).^[1]

The Unicode Consortium, the non-profit organization that coordinates Unicode's development, has the ambitious goal of eventually replacing existing character encoding schemes with Unicode and its standard Unicode Transformation Format (UTF) schemes, as many of the existing schemes are limited in size and scope and are incompatible with multilingual environments.

Unicode's success at unifying character sets has led to its widespread and predominant use in the internationalization and localization of computer software. The standard has been implemented in many recent technologies, including XML, the Java programming language, the Microsoft .NET Framework and modern operating systems.

Unicode can be implemented by different character encodings. The most commonly used encodings are UTF-8 (which uses 1 byte for all ASCII characters, which have the same code values as in the standard ASCII encoding, and up to 4 bytes for other characters), the now-obsolete UCS-2 (which uses 2 bytes for all characters, but does not include every character in the Unicode standard), and UTF-16 (which extends UCS-2, using 4 bytes to encode characters missing from UCS-2).

And you can find further information here ( http://en.wikipedia.org/wiki/Unicode ) and here ( http://unicode.org/ ).

VB.NET OpenFileDialog
I'm going to go out on a limb here and say that the VB.NET OpenFileDialog has to do with opening and saving files. In all seriousness though, according to VB Helper ( http://www.vb-helper.com/howto_net_use_restoredirectory.html ):

When you use an OpenFileDialog and the user changes directories, the dialog changes the application's current directory. If you set the dialog's RestoreDirectory property to True, then the dialog resets the current directory to its original value when it closes. Note that the dialog still keeps the new directory as its starting point the next time you display it.

UML Class Diagram
UML stands for Unified Modeling Language and is useful in all aspects of the design process as stated by Donald Bell ( http://www.ibm.com/developerworks/rational/library/content/RationalEdge/sep04/bell/ ):

Structure diagrams are useful throughout the software lifecycle for a variety of team members. In general, these diagrams allow for design validation and design communication between individuals and teams. For example, business analysts can use class or object diagrams to model a business's current assets and resources, such as account ledgers, products, or geographic hierarchy. Architects can use the component and deployment diagrams to test/verify that their design is sound. Developers can use class diagrams to design and document the system's coded (or soon-to-be-coded) classes.

This is one area that I will be looking into over the break starting at the end of this week.

I was also supposed to do a description of the cat and dog classes that we're working on at the moment, however, I need a little more information from Rachael to find out just what it is that she needs in the post.

So until then, I hope all's well for you.

All the best,

Tim.

Classes and Object in Visual Basic.NET

We were asked today to do a blog on classes and objects, so after doing some research, I have come up with the following information.

Visual Basic.NET is what is known as an Object Oriented language. This means that the programs designed using this language run based around a series of objects. The amount of objects will depend on the complexity of the program, but they must have at least one object (the "form") in order to run (not that you would do this as there's no point in having just a form pop up. It would serve absolutely no purpose.) No matter whether your program is designed to run in a windows, web or mobile application, it will have to have a form that it uses as a "container" for the rest of the program.

For example, a button is an object. It must be placed on a form before it can be used as part of a program. The button itself will have a click event which is part of the button class. To use an explanation from Free computer Tutorials:

A Class is the code itself; the code becomes an Object when you start using it.

In other words, when you place a button on to the form and double click it, Visual Studio will create a class that can be used for that object. You then take that class and add more code to it to make the button usable. A clear button as an example can have code that will cause it to clear other objects (such as textboxes and labels) in your program. For instance, you may have a textbox on your form which will cause a label to be displayed once the user clicks on the submit button. The clear button can then be made to clear the text from the textbox, clear the text in the label and put the focus back on the textbox ready for more input from the user.

In the instance above, the button class "clear" will do all or any of those things mentioned and in this case, becomes the Clear Button object.

I hope this hasn't been too confusing, and if you understand it, please explain it to me... :-)