(Leo Hsu and Regina Obe) A while ago we demonstrated how to create cross tabulation tables using tablefunc extension aka (Pivot Tables) (basically collapsing rows into columns). Recently someone asked me how to do the reverse (convert columns to rows).

(Rob Gravelle) This article is the second part in a series examining some of the challenges in porting your databases between MS SQL Server and MySQL. In Part 1, we looked at some of the differences between data types utilized by each DBMS. Today, in moving on to functions, you’ll see how function

(Josh Berkus) Cascading replication is a 9.2 feature which allows you to replicate through a chain of replicas. The master replicates to replica1, which replicates to replica2, which replicates to replica3, etc.

(Baron Schwartz) Those who’ve been around the MySQL world are probably aware of the much-discussed topics of GPL licensing, dual licensing, and in particular, licensing of the client libraries (also called connectors or drivers) and the FOSS exception to that licensing. This is newly relevant with t

(Bruce Momjian) Nulls exist in a three-valued logic system, which frankly sounds scary. A two-valued logic system, where things are either true or false, is very easy to understand. Three-valued logic sounds like something is wrong, and in an sense something is wrong because it injects uncertainty (

(Frederic Descamps) If you are using SElinux, you should know that it’s advised to disable it to avoid issue with PXC. Generally the communication between your nodes doesn’t work properly and a node having SElinux enabled won’t be able to join the cluster.

(Bruce Momjian) Having covered why nulls exist and how they can be created explicitly and implicitly, let’s look at how nulls behave by looking at some specific examples. I previously showed that you can specify null explicitly, but what happens when nulls interact with non-nulls:

(Miguel Angel Nieto) This is a recurrent question made by our MySQL Support customers:

(Baron Schwartz) I was just bitten by failing to catch a MySQL warning. It’s the old familiar tune: I inserted 100 characters into a VARCHAR(50) and it didn’t throw an error*. Of course, then subsequent SELECT statements didn’t find the value I inserted.

(Bruce Momjian) After my previous blog post about nulls, you might have decided to avoid null completely by never assigning them to your database columns. While this will reduce the number of nulls in your database, it will not eliminate them because various sql commands generate nulls as well.