Posted on in Software
In a test lab, we ran into a situation where the connection between our Cisco Access Registrar (AAA) server and MySQL server was timing out. This forced the server to reconnect and resulted in the following errors:
name/radius/1 Error Server 0 ODBC client (DataSource 'my_odbc', Connection 8): SQLExecute …Posted on in System Administration
We ran across the following error on a MySQL slave server recent:
mysql> SHOW SLAVE STATUS \G
<snip>
Last_Error: Query caused different errors on master and slave. Error on master: 'Deadlock found when trying to get lock; try restarting transaction' (1213), Error on slave: 'no error' (0). Default database: '<database_name …Posted on in Programming
If you need to debug what queries your WordPress site is making, try adding the
following PHP to your theme:
<?php
foreach ( $wpdb->queries as $query ) {
echo "$query[0]<br />";
}
?>
For this code to work, you need to add the following line to wp-config.php:
define('SAVEQUERIES', true);
After that …
Posted on in uncategorized
The following resources were used in the writing of the Introduction to Database Systems article series:
Posted on in Programming
In the early stages of an organization, it is common for most data to be stored in spreadsheets. Spreadsheet applications are common and easily understood by most small business people. Unfortunately, spreadsheets become burdensome when tasks move beyond calculations and into querying (Churcher, 2007). Fortunately, databases are designed with querying …
Posted on in Programming
The widespread use of computers has made database interaction a daily occurrence. Although databases can be large and complex, they are generally defined by basic terms that come together to create the larger system. Understanding these database basics helps users understand the underlying structure of the system and how they …
Posted on in Programming
Referential integrity and business rules are two subjects that individuals new to database design find confusing. Relational databases use tables to represent things and events. It is often necessary for a table to refer to another table. In this case, the two tables have a relationship. Referential integrity ensures that …
Posted on in Programming
For those not acquainted with the vernacular of relational databases, many frequently used terms can be hard to grasp. These terms are often difficult to comprehend, but the concepts they describe can be illustrated in plain English. When a database administrator or developer is working with someone not fluent in …
Posted on in Programming
A database is a collection of files used by an organization in support of its daily operations. The files in a database are commonly called tables because their data is organized into rows and columns. Databases allow for easy storage and retrieval of the data kept within the files that …
Posted on in Programming
This is a six-part introduction to database systems with a collected list of references at the end. These posts were derived from a set of papers I had to write for a business class.
Posted on in Programming
Database transactions are really no mystery. For the uninitiated, the idea is that we want to make changes to the database inside of a transaction that can be committed or thrown away. Why is this a good thing? Without transactions, changes to the database have to be manually undone if …
