SYSIBM catalog tables are base tables defined under this schema. There are many schemas defined in DB2. To your quick reading, I have given all the key points here.
Data access is much faster in Hashing compared to the index. Read the differences between Hashing and Index.
Having Vs Where clause in SQL real usage is to filter rows on aggregate totals. Read more.
Mostly asked certification questions in DB2. You need more focus on these areas before you take the test.
You need these tips handy when embedding DB2 database in application program like COBOL or PL/I
You need to know these SQL query and rules to delete a row from a Table in DB2 database