Friday, April 25, 2025

Have issues? Communicate! A brief look at Db2 SQLCA

Db2 command line output with printed SQLCA
With many conflicts and problems, big and small, going on, communication is important. So, why not take a brief look at the Db2 SQL Communications Area (SQLCA)? According to the Db2 documentation, an SQLCA is a collection of variables that is updated at the end of the execution of every SQL statement. It provides the structure to pass important information from the database product to the user or application.

Communication Area overview

The SQLCA is present across the Db2 platforms:

The structure consists of several fields that hold the product identifier, error code and state, error message and more. See the above links for details. Noteworthy are the field descriptions in the Db2 for i documentation because they include the list of product identifiers which are passed in the field SQLERRP. It is a CHAR(8)-sized field and the first three characters identify the product:

  • ARI for Db2 for VM and VSE
  • DSN for Db2 for z/OS
  • QSQ for Db2 for i
  • SQL for all other Db2 products

The Db2 LUW docs specify what follows after the "SQL", namely the SQLvvrrm with two characters for the version, two for the release and one for the modification. That information is returned when connecting to the database (see screenshot above). In my case I am on Db2 v12.1.1 (SQL12011). Some of the other fields have additional information on CONNECT. An example is SQLWARN7 which contains a "B" when successfully connected to BigSQL or "D" for Db2 Warehouse on Cloud.

Homework 

The above is just the overview and what is returned on the CONNECT to a database. There are many details in the structure and case-specific behavior. If you want to have some "Friday fun", use the Db2 command line processor (CLP) and start a database connection:
 
db2 -a "connect to testdb" 

The parameter "-a" (like in "area") prints the received SQL Communications Area. Next, try out some SQL statements, including some with syntax errors, no results and more...
 
That's it for today. If you have feedback, suggestions, or questions about this post, please reach out to me on Mastodon (@data_henrik@mastodon.social) or LinkedIn.
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