Thursday, November 27th, 2014

DatabaseNormalisation

If you store the same information in multiple places in a database then you run the risk of updating that information in one spot in the database and not updating it in another and then ending up with inconsistent information in the database. To avoid this happening we need to design our database properly in the first place so as to remove unnecessary redundancies and to identify those that still exist so as to make sure that our database update processes correctly update all occurrences of the redundant information.

So if we are going to identify all the redundancies then why not remove them all? Well in some cases the added complexity that results from the removal of the redundancy significantly slows processing and where the relationship is fairly static the issue of inconsistencies is nearly non-existent and so no benefit is obtained by removing that redundancy. One such example would be the relationship between the name of a given suburb/town and the post/zip code associated with it.

While we may want to deliberately allow some redundancies in our database for efficiency reasons the best place to start is to eliminate all the redundancies in our design and then once we have done that we put the redundancies back in that we decide we want.

The process of removing redundancies is called normalisation. In most cases there are only three steps you need to apply in order to remove the redundancies and a database design where the three steps have been applied is called third normal form (there are two different lists of the three steps that actually work completely differently but end up with the same result at the end of the third step). Just occasionally a database in third normal form will still contain redundant information and there are a further three normalisations that apply to specific arrangements of your data.

Database Normalisation

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    Wednesday, November 26th, 2014

    Primary Keys

    In applications that reflect things that exist in the real world there are seldom situations where there isn’t something that has a unique value that can be used as the primary key for a table in your database. Despite this many people who know nothing about database design always implement an autoincrement primary key which adds a collection of potential problems to their processing that would not exist if they selected the correct key.

    Primary Keys

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      Tuesday, November 25th, 2014

      doctype

      The SGML doctype is the only SGML tag that most people writing for the web ever see. Even those actually creating the browsers seem to not understand what it is for since even though HTML 2 was rewritten to comply with SGML, even now no browser has been redesigned to actually use it to determine what tags the document expects to use. Sine no browsers use it, HTML 5 has abandoned SGML completely. XHTML 5 does still continue to comply with XML but in XML the SGML doctype is optional.

      doctype

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        Monday, November 24th, 2014

        PHP Pocket Reference, 2nd Edition

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        PHP Pocket Reference, 2nd Edition : Rasmus Lerdorf: Book

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          Monday, November 24th, 2014

          Deprecated

          While professional programmers know what ‘deprecated’ means, many others don’t. Those writing code to run on the server get caught out when they continue using deprecated code in their scripts and the new version comes out having removed those commands (as was previously identified by flagging those obsolete commands as deprecated). In order to not break 95% of web pages that are still being written using tags that were flagged for removal long ago those tags have been downgraded to ‘obsolete’ and browser support retained – at least for the moment.

          Deprecated

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            Sunday, November 23rd, 2014

            Selecting Scripts

            I have added this page to the HTML section of the site even though it is about JavaScript because the intended audience are those people who want to be able to use a script written by someone else with their site and who don’t actually know or want to learn JavaScript themselves. This page gives a few hints about the sorts of things to look for in the code that will help you to choose the better written script that is more likely to be supported in the future.

            Selecting Scripts

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              Saturday, November 22nd, 2014

              Types of Hosting

              What type of hosting do you need for your web site? If you don’t know the answer to that question then you have come to the right place. Find out what the difference is between “free”, shared, reseller, VPS, dedicated, and co-location hosting options.

              Types of Hosting

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                Saturday, November 22nd, 2014

                Modern PHP

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                Modern PHP : Josh Lockhart: Book

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                  Friday, November 21st, 2014

                  What Time is it?

                  Things can get very complicated when it comes to working out the current time in connection with things on the internet such as web pages and emails. There is the current time where you are. There is the time where the server is where a web page is hosted. There is the time at the location where the person who wrote the web page is located. For emails there are possibly different times for the sender and recipient of an email as well as the times where the various mail servers involved in the delivery of the mail are located.

                  All of these times can be different and may or may not have any meaning to you. For a specified time to have meaning you need to know which of the various times that it is that you are looking at and also what timezone it is. In addition you need to know whether or not that location has daylight saving time and whether or not it currently applies.

                  What Time is it?

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                    Thursday, November 20th, 2014

                    HTML Reference

                    This is an (X)HTML summary listing all of the (X)HTML tags and the attributes that each supports. The list excludes those tags and attributes that have been deprecated or which were never part of the standards in the first place. Those which are mandatory, those which are optional but which ought to always be used to make the code easier to maintain, those which ought to be deprecated, and those which browsers do not yet support are all marked with different codes to help you to work out which tags and attributes that you should be using in your web pages. Those tags proposed in HTML 5 which have yet to become a part of the standard are excluded. You should consider using those only where the current standard does not provide an equivalent tag.

                    HTML Reference

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                      Wednesday, November 19th, 2014

                      PHP and MySQL Web Development

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                      PHP and MySQL Web Development : Luke Welling,Laura Thomson: Book

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                        Wednesday, November 19th, 2014

                        Arrays, argumentsandNodes

                        This article looks at the arguments list available to functions and at node lists returned from some DOM calls and explains how they are not arrays and what you would need to do to be able to process them as arrays.

                        Arrays, arguments and Nodes

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