Oracle Error PLS-00489: invalid table reference: ‘string’ must be a column in this expression

Oracle Error Message

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

Reason for the Error

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

Solution

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.