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Welcome to Datavail’s Blog, where you can read the latest insights, tips and opinions of our experts on all things data and technology.

Author: Craig Mullins
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On Date Formats in DB2 – Part 2

Here is a follow-up question and answer based on my previous blog post: Q: My format does not fit into any of the formats listed in the DB2 manuals. What if I have a DATE stored like YYYYMMDD (with no dashes or slashes) and I want to compare it to a DB2 date? A: Okay, let’s look at […]

Craig Mullins | February 18, 2016

On Date Formats in DB2 – Part 1

Regular readers of my blog know that from time to time I use the blog as a forum to answer questions I get via e-mail. Today, we address a popular theme – dealing with DB2 date data…

Craig Mullins | February 9, 2016

DB2 Date and Time Data

DB2 allows you to add and subtract DATE, TIME, and TIMESTAMP columns. In addition, you can add date and time durations to, or subtract them from, date and time columns.

Craig Mullins | January 26, 2016

Q+A: Locking

The question was: I want to perform a retry on an INSERT under DB2 Z/OS when I get a deadlock/timeout. -911 causes a rollback automatically.

Craig Mullins | December 24, 2015

Consider Table Expressions to Improve Performance

Table expressions are frequently overlooked as a potential solution for resolving problems using only SQL.

Craig Mullins | December 23, 2015

Database Performance and Row Size for DB2

Recently I was reading through some posts on a database-related blog or mailing list (actually, right now I can’t remember which one it was). The conversation I was reading was in response to this question: “Does the number of columns or size of the row matter in terms of performance?”

Craig Mullins | December 18, 2015

Q+A: Nulls and DASD

Let’s say I have a table A which has 500 columns. Out of those 500 columns only 5 columns have been defined as not nullable and the rest have been defined as NULLS allowed.

Craig Mullins | December 14, 2015

VARCHAR versus Compression

This blog will compare the use of VARCHAR to DB2 compression when you are building your DB2 databases. Visit to learn more.

Craig Mullins | October 27, 2015

Evaluating DB2 Tool Vendors

You should really do the investigative work required to find out the real level of support for DB2 V11 that is in the GA version of the tool. Read more.

Craig Mullins | September 1, 2015

Adding Column Names to an Unload File

Are any of the DB2 unload utilities able to include the column names in the same file as the unload output data? Read on to discover the answer.

Craig Mullins | August 19, 2015

Advice on Using Variable Character Columns in DB2

One of the long-standing, troubling questions in DB2-land is when to use VARCHAR versus CHAR. The high-level advice for when to use VARCHAR instead of CHAR is for larger columns whose length varies considerably from row-to-row. Basically, VARCHAR should be used to save space in the database when your values are truly variable. In other words, if you have a 10-byte column, it is probably not a good idea to make it variable… unless, of course, 90% of the values are only one…

Craig Mullins | August 4, 2015

Returning Only Numeric Data

We want to examine CHAR data but return only those where the entire data consists only of numbers. For example, can we write a query like this?

Craig Mullins | May 26, 2015

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