Connecting to MySQL from Python offers many solutions, but I like the official MySQL connector. You can install the module using pip.
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Combinatorial row pairing in databases
While working on a database design I came across the problem of finding combinations or ‘cartesian product’ between all the rows between one table to another table, but not repeating the same permutations.
Take the ‘Teams’ table below which lists four cricket teams. We want to create a combination list of matches between each teams.
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How to calculate the size of a MySQL database
Many times we need to calculate the size of a MySQL database through code for purpose like database backup or to check how fast the database is growing for a certain application. The database size can be easily ascertained using phpmyadmin or other desktop tools, but that requires you to manually launch the tool and check. Below we will see how to do the same through a query.
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How to profile and debug MySQL queries for speed
Most MySQL applications need profiling for speed enhancements at one time or other. I’ve developed several web applications in the past wherein MySQL queries were a major bottleneck in the application performance. In the past however there were no easy tools to analyse SQL queries in a running application and we programmers had to depend on some makeshift solutions to debug SQL queries. Now, however there are some nice free tools which can help you profile MySQL application queries easily.
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Data Quality in web applications
There is nothing painful than having to rebuild a database after you find that the records in the database are corrupted. Data corruption in databases can take many forms – from allowing inaccurate data to be entered to data field truncation due to inadequate field length. This post gives an introduction to the data quality issues you will encounter when designing database applications.
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How to automatically backup MySQL database to Dropbox
Ever wanted to backup your MySQL database to Dropbox automatically. Well, there is a nice portable solution with Dropbox Uploader. Dropbox Uploader is a BASH script which can be used to upload, download, delete, list files, move, copy and much more from Dropbox. It’s written in the BASH scripting language and only needs cURL to work. I’ve tested it on my Windows/Cygwin environment at it works like a charm.
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MySQL transactions in NodeJS
In a previous post we saw how to access and query MySQL from NodeJS. In this post we will see how we can use MySQL transactions in NodeJS. We will be using the same library as used before, so if you have not installed it go ahead and install it. The library supports simple transaction at the connection level.
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Export a subset of a database table to reproduce a query
One frequently needs to export some MySQL tables along with certain queries that will work with that table for testing. Usually one only needs a subset of records from the table which will work with the selected queries, rather then the complete table. This can be required when the table contains thousands or millions of records and we do not want to export the complete data set, as this can be time consuming during import, or maybe we only want to provide the other user with some selected records for security reasons.
Say we have a simple WordPress database with a SELECT statement like the following:
SELECT * FROM wp_posts WHERE post_status = 'draft' |
If you want to only export records that will match the corresponding query above, then we can use the ‘mysqldump’ command-line utility with the ‘–where’ option.
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