Question

Will the following statement work?

SELECT department_name, last_name
FROM employees, departments
WHERE department_id = department_id;
A.No, Oracle will return a Column Ambiguously Defined error.
B.Yes, Oracle will resolve which department_id colum comes from which table.
C.Yes, there are no syntax errors in that statement
D.No, Oracle will not allow joins in the WHERE clause

Answer 1

The statement mentioned above will not work because when Oracle encounters this scenario without explicit clarification, it will generate a "Column Ambiguously Defined" error. Option "A. No, Oracle will return a Column Ambiguously Defined error," is correct.

Step-by-step explanation:

In SQL, when columns with identical names exist in multiple tables involved in a query, it's crucial to specify which table's column to use to avoid ambiguity. The provided SQL statement selects the department name and last name from the employees and departments tables but doesn't specify which department_id column to use for the comparison in the WHERE clause. This lack of specificity causes ambiguity for Oracle in determining which table's department_ id should be considered.

When Oracle encounters this scenario without explicit clarification, it will generate a "Column Ambiguously Defined" error because it cannot definitively determine which column to use. To resolve this issue, the query should be modified to specify the table for the department_ id column in the WHERE clause, like "employees. department_ id = departments. department_ id," ensuring Oracle can correctly associate the columns from their respective tables.

Correct answer: A. No, Oracle will return a Column Ambiguously Defined error.