Why do I have ORA-00904 even when the column is present?

Oracle will throw ORA-00904 if executing user does not have proper permissions on objects involved in the query.

Write the column name in between DOUBLE quote as in "columnName".

If the error message shows a different character case than what you wrote, it is very likely that your sql client performed an automatic case conversion for you. Use double quote to bypass that. (This works on Squirrell Client 3.0).

This happened to me when I accidentally defined two entities with the same persistent database table. In one of the tables the column in question did exist, in the other not. When attempting to persist an object (of the type referring to the wrong underlying database table), this error occurred.

ORA-00904-invalid identifier errors are frequently caused by case-sensitivity issues. Normally, Oracle tables and columns are not case sensitive and cannot contain punctuation marks and spaces. But if you use double quotes to create a quoted identifier, that identifier must always be referenced with double quotes and with the correct case. For example:

create table bad_design("goodLuckSelectingThisColumn  " number);