-7023: Dropping of all columns not allowed 

Explanation:

You tried to delete every column from a table. This is not allowed.

User Action:

...

       1.      Delete the table using the DROP TABLE statement. This deletes all view tables, privileges, indexes, referential CONSTRAINT definitions, etc. that depend on this table.

       2.      Afterwards, use the CREATE TABLE statement to define a new table with the same name.