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For some unknown reason when I first started writing mainframe JCL articles I ended up writing quite a few about Generation Data Groups of which this one was the first.

What is a GDG?

There have been a number of variations to my calendar script over the years since I first created it as a calendar popup. While much of the actual code in the script has been altered several times in order to make it far more flexible than it was originally, it can still be used for its original purpose of creating a popup window containing a calendar.

Creating a Calendar Pop-up

While a conventional if statement is relatively easy to read, it can be a bit long-winded in what you need to type in order to make decisions. Where the decision that is to be made is which of two or more possible values is to be assigned to a specific field, JavaScript provides an alternative notation that can be used to combine the decision making process into the assignment statement itself. This shorter way of defining an if else condition can’t be used just anywhere and it is not as easy to read as a normal if statement but it is much shorter to write and should lead to more efficient processing in those situations where it can be used.

A Shorter IF Statement

Sometimes there are more than two possible outcomes that you want to process depending on which particular combination of conditions apply. By nesting if statements inside of other if statements you can tell JavaScript which outcome to apply when the appropriate combination of decisions are made.

Nesting If Statements

Continuing on the series of tutorials on Making Decisions in JavaScript, this eighth tutorial looks at the logical operators AND, OR, and NOT and how they can be used to combine conditions together into a single test.

Multiple Tests – And, Or, and Not

The one time that your visitor’s screen resolution is relevant is when you are opening a new window. When you specify the size and position for the new window you need to make sure that it fits on the screen in the place you want. This early JavaScript tutorial was one of the first that I wrote specifically to answer a question that was asked by a visitor to the site (I have of course answered many more questions since then and a few hundred have even ended up as web pages).

Assigning an Absolute Screen Position Independent of Screen Resolution

It looks like Microsoft did not proceed with the planned forced upgrade to IE 7 on 12th February as they had previously indicated was scheduled. As yet I have found no explanation for why this didn’t happen. Given that IE 7 is actually a major security patch to IE 6 is ought to have been a “must have” upgrade from day one but for some reason Microsoft do not seem to want to push this anywhere near as much as they ought to be doing.

I have just been comparing the recent browser stats for my site with those from a few months ago and the comparison is quite interesting. The percentage of visitors to my site who use IE 7 has actually fallen from 29% to 26% over the past few months while IE 6 users remains relatively static at 27%. This means that once more there are more IE 6 visitors than IE 7 visitors. It also appears to indicate that people have stopped upgrading from IE 6 to IE 7 and that those who did upgrade to IE 7 have started upgrading again to a better browser than IE. The combined toal for IE visitors is now down to 54% while those using Firefox and Mozilla are now at 41%. Opera and Safari users make up most of the remainder.

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All relational databases support Structured Query language (abbreviated SQL - pronounced Sequel). The most commonly used statement in SQL is the select statement which is used to extract data from the tables and views in your database for use in your program. This article looks at all of the component parts of a select statement and how they are used to allow exactly the data that is required to be retrieved from the database in the most efficient way possible without retrieving any unnecessary data with it.

Select Statements