Eine Einführung in

SQL

CREATE TABLE problems: Invalid column name.

Oracle

You may not use a reserved word as the name of a field. Many popular words are used by the system; some words to avoid...
date, day, index, number, order, size, year

SQL Reserved words

Having a "house-rule" can prevent such problems. Some developers insist that field names begin with fld for example fldSurname. Most of us have enough meaningless junk in their lives already; we don't need this kind of self imposed tyranny.

Execute tidy up code silently


Specific to Oracle
You may not use DATE or SIZE or INDEX or NUMBER or ORDER or SIZE as a field name.