There is plenty of documentation out there for DB2. Still here are some commands I needed.

Show all DB2 Tables

SELECT * FROM syscat.tables

Show DB2 Table structure

SELECT NAME,COLTYPE,NULLS,LONGLENGTH FROM SYSIBM.SYSCOLUMNS where TBcreator ='SCHEMANAME' and TBNAME ='TABLENAME'

Show only first 10 results

select * from SCHEMANAME.TABLENAME fetch first 10 rows only

Example for updating a value of a column (STATUS) in a dataset (ID 123)

 update SCHEMANAME.TABLENAME set STATUS='NEW' WHERE ID=123 

Delete a row

DELETE FROM DSN8A10.EMP WHERE ID = 1