Procedural languages provide the fundamental method for programming within an SQL database. In other articles in this series, we have covered the SQL-based procedural languages, but those are generally not the only procedural languages found in an SQL database. Procedural extensions for Perl and Java tend to be the most popular additions, but some database Read more

SQL Programming Overview In the article SQL Programming, we discussed creating the “Hello, World!” function in PostgreSQL, MySQL, and Oracle. In this article, we take “Hello, World!” one step farther and introduce the parts of a function and how to pass parameters to a function. This article uses PostgreSQL’s PL/pgSQL Read more

SQL Programming Overview Anybody who has done something for a long time has probably wanted to change how things work at some point or another. A worker at a mill might have found a more efficient way of cutting logs, or a mathematics teacher might have had a hand in changing a school’s algebra curriculum. SQL lets you change how things work, Read more

Distributed Databases Overview Suppose you created a database for a web application a few years ago. It started with a handful of users but steadily grew, and now its growth is far outpacing the server’s relatively limited resources. You could upgrade the server, but that would only stem the effects of the growth for a year or two. Also, now Read more

Database Concurrency and Reliability Overview Concurrency and reliability have long been “hot topics” of discussion among developers and users of distributed systems. The fundamental problem can be seen in a simple example, as follows. Suppose two users are working on the same part of a database at the same time. They both UPDATE the Read more

What is a Relational Database? Popular, modern databases are built on top of an idea called “relational algebra”, which defines how “relations” (e.g. tables and sequences in databases) interact within the entire “set” of relations. This set of relations includes all the relations in a single database. Knowing Read more

SQL Keys Overview In SQL, keys are used to maintain referential integrity among relations. Put simply, this means keys allow tables to reference each other, and each reference will be “correct” every time. Referential integrity also prevents records from being “dangled” or “orphaned” by another record that has been Read more

SQL Table Commands Overview As mentioned previously in this series of SQL articles, databases are primarily composed of tables. The “columns and rows” structure of the table allows data to be efficiently inserted, manipulated, updated, and deleted from the database. The three most important commands used to work with tables, CREATE TABLE, Read more

SQL Overview The SELECT command in SQL provides a robust means for retrieving data from a database. More specifically, SELECT returns a result set of zero or more rows from the database, and this result set corresponds to the query that was executed. The result set is calculated by the query optimizer inside the database system, based on the information Read more

Database Overview You have been using databases for a few years, and you think you are at the top of your game. Or, perhaps, you have been interested in databases for a while, and you think you did like to pursue a career using them, but you do not know where to start. What is the next step in terms of finding more rewarding education and employment? There Read more