JavaScript: innerHTML

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In the following short post, we are going to take advantage of JavaScript and its innerHTML method.

Every DOM element can be manipulated using JavaScript. With the use of jQuery we can do great things, but if we need to do something more basic, it is probably better to use JavaScript directly, without the help of the aforementioned great library.

We can manipulate any DOM element using its id as selector together with document.getElementById. The advantage is that we can manipulate the inner html part of the element.
Let's see some example.

CSS: visibility: hidden vs display: none

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Writing for the web thought becomes more complicated everyday. It goes down to the fact that I've wrote more than 380 posts since July 2010 and thinking about new things to talk about is getting harder and harder. However, some times a short conversation with a friend or a colleague might ignite a sparkle and might give me new ideas for a short post like the following.

I was in fact talking with a friend when it came to my mind that the difference between visibility and display properties in CSS is some times completely missed. Specifically, the difference between visibility: hidden and display: none.
The point is not that complicated, so in just a few words we are going to see the difference, and we are going to explore when to use visibility instead of display.

SQL: AND vs OR (operators)

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In SQL Server we can use different operators in our queries: AND, OR, LIKE, BETWEEN and so on. In this short post we are going to see AND and OR because I've noticed that some could get confused by the results obtained when using them.

So, let's clear the situation a bit, because we really need to know what we are doing!

ASP: URL Rewrite and IIS7

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Following a kind suggestion by a follower, today we are going to see how to use IIS URL Rewrite 2.0 for IIS 7.

First of all, what's URL Rewrite?

"IIS URL Rewrite 2.0 enables Web administrators to create powerful rules to implement URLs that are easier for users to remember and easier for search engines to find. By using rule templates, rewrite maps, .NET providers, and other functionality integrated into IIS Manager, Web administrators can easily set up rules to define URL rewriting behavior based on HTTP headers, HTTP response or request headers, IIS server variables, and even complex programmatic rules. In addition, Web administrators can perform redirects, send custom responses, or stop HTTP requests based on the logic expressed in the rewrite rules."

Rest assured, we can use it for a classic ASP site as well.
What we need to do is:
1) install URL Rewrite after downloading it from the Ms IIS site;
2) enable ASP.NET role service on IIS 7;
3) write a rule

jQuery: chaining!

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We should all bless jQuery. It gives JavaScript a completely new face in terms of usability and easiness.
Considering the latest news about version 2.0, jQuery is quite alive and kicking...

I don't know how many of you know about chaining, but I think we should all try to understand how and why we should use it while writing jQuery code.

SQL: which columns should have an index

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In SQL tables might have primary keys and indexes. The primary key identifies each record. The key must be unique, it can't be NULL and each table must have just one key.
Indexes are something different: they are used to speed up the queries on a specific table. That means we absolutely need indexes on large tables which we often query.

SQL: subqueries

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In this short post, I would like to introduce the concept of subqueries in SQL.

A subquery is a query statement inside another query statement. As you already know the order in which a statement is processed is quite important. That is a basic rule like in maths: writing something like 2+2*5 is different than writing (2+2)*5. The first operation gives 12, the second 20.
In SQL the principle is identical.