Month: October 2013

Performance Load Testing with Visual Studio 2012 – Validating your data source file


a developer's notes - a semi-technical web development BLOG

Whether you are performance testing a web application or web service, you don’t want bad input data included in your test. This may skew your HTTP response times or simply add to the list of Errors that are captured during your performance test. Ideally, we want to have all clean and working input data so that any errors reported are not because of the data the test is using for a HTTP request. But sometimes we have data that has not yet been tested. So how do we clean up this data so that our test only uses input data that has been confirmed to work? One way to solve this problem is to use Visual Studio web tests to filter out any data issues from your data set using the following techniques.

In this post, I have created a simple Web Test plug-in that will write to a text…

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MySQL CheatSheet


AmpySPhR

Short List of MySQL Commands

Conventions used here:

  • MySQL key words are shown in CAPS
  • User-specified names are in small letters
  • Optional items are enclosed in square brackets [ ]
  • Items in parentheses must appear in the command, along with the parentheses
  • Items that can be repeated as often as desired are indicated by an ellipsis …

Quoting in MySQL statments

  • Don’t quote database, table, or column names
  • Don’t quote column types or modifiers
  • Don’t quote numerical values
  • Quote (single or double) non-numeric values
  • Quote file names and passwords
  • User names are NOT quoted in GRANT or REVOKE statements, but they are quoted in other statements.
General Commands
USE database_name
     Change to this database. You need to change to some database when you first connect to MySQL.
 
SHOW DATABASES
     Lists all MySQL databases on the system.
 
SHOW TABLES [FROM database_name]
     Lists all tables from the…

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Date Range Generator


ncorona

Working on databases I usually find very frustrating the differences that there are in the provided DBMS’s packages.

Except for the (not so much) standard guaranteed by the SQL language, there are a lot of differences in the syntax used to declare a function in the procedural language. Things even go worse working on spatial extensions of some famous DBMS. In particular I have found some difficulties passing from postgreSQL to MySQL DBMS, especially when declaring procedures and looping over queries’ results (MySQL is sooooo painful with its cursors!!! :-[  ).

In one task, I had to generate a range of dates. in particular I needed to generate a date for every day in a provided interval/range. This could be done in postgreSQl using a function for the generation of series like described here! Unfortunately there is no equivalent form in MySQL -.-‘  So I decided to create a…

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Data Preparation for Machine Learning using MySQL


The Official Blog of BigML.com

Most Machine Learning algorithms require data to be into a single text file in tabular format, with each row representing a full instance of the input dataset and each column one of its features. For example, imagine data in normal form separated in a table for users, another for movies, and another for ratings. You can get it in machine-learning-ready format in this way (i.e., joining by userid and movieid and removing ids and names):

Denormalizing (or “normalizing” data for Machine Learning) is a more or less complex task depending on where the data is stored and where it is obtained from. Often the data you own or have access to is not available in a single file—may be distributed across different sources like multiple CSV files, spreadsheets or plain text files, or normalized in database tables. So you need a tool to collect, intersect, filter, transform when necessary, and…

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