Category: MySql

Help and howto do things in MySQL

MySQL is the world’s most popular open source database, recognized for its speed and reliability, and is frequently used with PHP to create websites. The Electric Toolbox website uses MySQL as its database backend, and I have personally been using MySQL since 1999. In that time it has proven itself to me to be an extremely fast and reliable database management system, although the earlier versions lacked some features found in other database systems, such as stored procedures, triggers, sub selects and joined table updates. Most of these are available from the 4.1 and 5.0 releases.

If you are looking for MySQL databases – for example geographical databases, I suggest you take a look at SQL Dumpster

MySQL: order a string column as an integer

If you order a string column that contains only numeric values with MySQL, it will order them as string values, e.g.: 1, 10, 100, 2, 3, 31, 32, 4, etc. If you want to order them as if they were an integer, cast them in the order by clause.

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MySQL error can’t open file – errno: 24

After some maintenance was done to the virtual host server that one of my virtual servers was running on that required a host reboot, my websites weren’t running due to the MySQL error "[ERROR] /usr/sbin/mysqld: Can’t open file: ‘./databasename/tablename.frm’ (errno: 24)"

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How to find and replace text in a MySQL database

There are a few posts on this blog about the Facebox jQuery plugin, and as I discovered this morning the website URL for the plugin has changed so I needed to update all links to it. The quickest way to do this was to update the MySQL database directly using UPDATE and REPLACE to find the old URLs and replace them with the new URLs. So here’s how to find and replace text in a MySQL database.

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MySQL connections and PHP forked processes

It is possible to fork a process with PHP and have one or more child processes running. If a connection has already been established to a MySQL database and the child processes run queries it’s quite likely a "MySQL server has gone away" or a "Lost connection to MySQL server during query" type error will occur.

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