table structure changes

Change field length:

ALTER table schema.table_name ALTER column_name set data type VARCHAR(10);

call sysproc.admin_cmd('reorg table schema.table_name ');
call sysproc.admin_cmd('runstats on table schema.table_name with distribution and indexes all');

Add fields:

ALTER TABLE schema.table_name
ADD COLUMN column_name VARCHAR(100) NOT NULL WITH DEFAULT '*'; 

Add comment: 
COMMENT ON COLUMN TM_SEAT_ETERM_AUTHORITY.AGENT_AIRLINE 
IS 'Agent airline';