Tutorials by ONLamp.com
John Paul Ashenfelter looks at a specific class of SQL functions that operate on entire columns of data instead of discrete values -- the aggregate functions.
March 18,
2010
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Quick--what's the relationship between the columns of your database? Don't know? Maybe it's time to pull out the information theory book and calculate how much data they store.
March 10,
2010
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John Paul Ashenfelter looks at how keys are used to construct relationships between tables in a relational database.
March 9,
2010
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Suppose you need to calculate constantly-changing information based on constantly-updated information in one or more tables. Are you stuck doing everything in multiple expensive queries? By no means.
March 5,
2010
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Luminaries from the open source communities of Perl, Python, PHP, MySQL, Apache, and Linux each presented their take on the current state of their technology and where it is headed.
February 26,
2010
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Application upgrades aren't always easier. Throw in a database backend and a schema change, and you're in for a world of hurt -- unless you've planned well. Russell Dyer explores techniques for taking the pain out of upgrading database-backed applications.
February 23,
2010
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In the last aboutSQL column, John Paul Ashenfelter introduced the Data Definition Language (DDL) and how to create database containers. This week, he moves on to creating tables and populating them with data.
February 18,
2010
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Although there are several tools available to help users efficiently and easily create pivot tables or cross-tabulations, being able to visualize the cross-tabulations in real time is much more useful.
February 16,
2010
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The most popular "proper" way to build a web application seems to be to use the Model-View-Controller design pattern. While it sounds complex, the concepts are sound and the ease of development it provides are compelling.
February 11,
2010
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Type; reload web site; eyeball output; fix bugs; repeat--there's a better way to write PHP code! Testing gives you confidence not only that your code works, but also that you can make changes to improve your design and flexibility without breaking behavior.
February 4,
2010
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