Joe Celko is one of the most widely read of all writers about SQL, and was the winner of the DBMS Magazine Reader's Choice Award four consecutive years. He is an independent consultant living in Austin, TX. He has taught SQL in the US, UK, the Nordic countries, South America and Africa.
He served 10 years on ANSI/ISO SQL Standards Committee and contributed to the SQL-89 and SQL-92 Standards.
He has written over 800 columns in the computer trade and academic press, mostly dealing with data and databases. He is the author of eight books on SQL for Morgan-Kaufmann, including the best selling SQL FOR SMARTIES.
Joe is a well-known figure on Newsgroups and Forums, and he is famous for his his dry wit. He is also interested in Science Fiction.
The SQL NTILE() is a window function that allows you to break a table into a specified number of approximately equal groups, or <bucket count>. For each row in a grouping, the NTILE() function assigns a bucket number representing the group to which the row belong starting at one. The syntax of the NTILE() function … Read more
Dr. Codd first described the relational model in a paper in Communications of the ACM (CACM 13 No 6; June 1970). Some more work followed up after that by other people, giving us normal forms and other things we have taken for granted for 50+ years. I was looking at some postings on a SQL … Read more
When you’re learning SQL DML, the most complicated clause is typically the GROUP BY. It’s a fairly simple grouping based on values from the FROM clause in a SELECT statement. It’s what a mathematician would call an equivalence relation. This means that each grouping, or equivalence class, has the same value for a given characteristic … Read more
In this article, Joe Celko gives us a history of the different character sets that are used in computing and how that can pertain to your usage in relational databases. Some of these you may have never heard of!… Read more
To prevent data change anomalies, a database should be normalized. Did you know that there are 10 normal forms? In this article, Joe Celko reviews normalizing databases including commonly used normal forms.… Read more
Dr. Codd proposed the normalization rules we used to design databases, but did you know that he also came up with rules that vendors must meet to call their products relational database systems? In this article, Joe Celko explains the thirteen RDBMS rules.… Read more
The logic for referential integrity can be implemented in application code, but to make sure that it is enforced, include foreign key constraints in the database design instead. In this article, Joe Celko talks about the history of references in SQL and the options available today. … Read more
Understanding scoping rules is a basic skill for developers. In this article, Joe Celko gives a bit of the history of scoping in early programming languages and shows how scoping applies to SQL queries as well. … Read more