Can't think of anything, to be honest. This is probably my least favorite database system to use out of the following list: MS SQL Server, MySQL, SQLlite, Elastic, Hadoop, Oracle, Teradata, etc. Would rather use any of these than IBM DB2. Review collected by and hosted on G2.com.
You can't declare global variables, after using more than 5 different databases this is the first I've come across that does not support them. There is no online support or documentation that can give you the answer you are looking for. It does not support PIVOT/UNPIVOT functions so you are not able to transpose anything. This system was big in the '80s and died in the '80s. After showing clients who use DB2 a different database system (literally any, didn't matter which really) they were blown away and instantly started transitioning away from DB2 and on to the new system. Review collected by and hosted on G2.com.