|ORA-00904:||string: invalid identifier|
|Cause:||The column name entered is either missing or invalid.|
|Action:||Enter a valid column name. A valid column name must begin with a letter, be less than or equal to 30 characters, and consist of only alphanumeric characters and the special characters $, _, and #. If it contains other characters, then it must be enclosed in double quotation marks. It may not be a reserved word.