Guest Columnist: Joe Celko

In the first level of his Stairway to SQL Dialects, Joe Celko looks at the origins of the SQL language and how the language has spawned the various different dialects in use today.  Read more...

As part of the LAMP stack, MySQL is incredibly important for providing a reliable and platform-agnostic database platform for web development. This level looks at the syntax of MySQL and how to best port SQL code to a MySQL environment.  Read more...

Level 2 of this stairway explains how to convert data declaration language (DDL) statements and data manipulation language (DML) statements from Postgres to Microsoft SQL Server.  Read more...

In the final step of Database Design, Joe Celko gives a simple but effective explanation of the normalization process and why it is important.  Read more...

Joe Celko discusses Nominal, Categorical, Absolute, Ordinal and Rank scales. These are the weakest scales we can use, starting with the weakest.  Read more...

Joe discusses Hierarchical, Vector and Concatenation encoding before rounding up with general guidelines for designing encoding schemes.  Read more...

Joe discusses how to deal with the kinds of encoding schemes, how to use them and how to design them. He discusses Enumeration, Measurement, Abbreviation and Algorithmic categories   Read more...

Joe Celko introduces more powerful scales such as Interval, Log interval and ratio scales; before moving on to conversions, punctuation and units. Finally he gives guidelines as to how best to use scales in a database.  Read more...

Joe Celko tackles the most difficult of all the types of data handled by SQL, temporal data, and explains how to avoid the commonest traps for the unwary programmer  Read more...

Character-handling in SQL is not particularly straightforward, and confusion about collation and character encoding is a common cause of problems with searching, joining, and sorting.  Read more...

A confusion about the nature of numbers can lead to a number of problems in database applications. Joe Celko gives a simple guide to the subject  Read more...

A great deal of the confusion that occurs when a database application is developed comes from a poor understanding of the basics of data. Here, Joe Celko gives a broad coverage of the difficulties you're likely to meet when handling data in databases  Read more...

This final level to the first landing completes the basics of a SQL database, by explaining what cursors are and why you should never use them.   Read more...

In levels one to four, we built the tables, base and virtual, of a schema. Levels five and six dealt with stored procedures. This level deals with a feature you need to avoid as much as possible; this is article is on Triggers.  Read more...

Having covered the procedure headers in SQL Server in the previous level, Joe tackles the subject of the contents of stored procedures. In this level, he outlines limitations of TSQL as a procedural language, and what you need to bear in mind when deciding how to use them.  Read more...

Joe Celko tackles the subject of the Stored Procedure and its place in database design. What he writes is food for thought, even for experienced database developers.  Read more...

Having described tables, Joe Celko explains how to make them work together as a database and touches on what Entity Relationships and Views are.  Read more...

There are several types of tables, each with their special requirements for rules and integrity constraints. Whatever the requirement, table-level constraints will ensure that the rules are enforced and data integrity is maintained.  Read more...

A clear understanding of SQL Data Types and domains is a fundamental requirement for the Database Developer, but it is not elementary. If you select the most appropriate data type, it can sidestep a variety of errors. Furthermore, if you then define the data domains as exactly as possible via constraints, you can catch a variety of those problems that would otherwise bedevil the work of the application programmer.  Read more...

Before you start to think about your database schema or tables, you need to consider your data: the type of data it is, the scale you use for values. It needs to be unique, precise and unambiguous. Then you need to name it in such a way that it can be generally understood. Joe Celko explains...  Read more...