SELECT colname, typename, length, scale, default FROM syscat.columns WHERE tabname = “<table name>” AND tabschema = “<schema name>”
See also:
How to get column names from Sql Server table
How to get column names from Oracle table
How to get column names from Mysql table
How to get column names from PostgreSQL table
How to get column names from SQLite table
Some DB2 tools you can try: https://www.withdata.com/db2/