PLS-00489: invalid table reference: string must be a column in this expression

PLS-00489: invalid table reference: string must be a column in this expression

Cause: In a query, a select-list item refers to a table in the FROM clause but not to a database column.

Action: Check the spelling of the column names, make sure each column in the select list refers to a table in the FROM clause, then re-execute the query.