| 2 | Quarry | Bedrock || 5 | Rubble | 2 | | 3 | Stockpile | Redcliff || 7 | Rockhead | 3 | +---------+----------------+----------+| 11 | Gravel | 1 | +---------+------------+------+ There is a department number field in both the EMPLOYEE and DEPARTMENT tables. In the EMPLOYEE table, the department number represents the department in which the employee works. In the DEPARTMENT table, the department number represents a valid department within the business. In both tables, they are department numbers; in essence, the contents of the DEPT field in the EMPLOYEE table represents the same thing as the contents of the DEPT_NO field in the DEPARTMENT table. It's not necessary that the linking fields have the same field names. What's important is their value and what they represent. The business is divided into departments. The departments are identified and stored in the DEPARTMENT table. Each department is assigned a department number. The relationship between the EMPLOYEE and DEPARTMENT tables is based on the department number. Each employee works in one specific department. The employee's department number is stored in the DEPT field of the EMPLOYEE table. An employee cannot be assigned to a department that is not defined in the DEPARTMENT table. A department can be defined in the DEPARTMENT table, yet have no employees assigned to it. Foreign KeyRemember that every table in ORACLE has a primary key a field or fields making each record unique. In the employee table, the primary key is the employee ID number, and it is stored in the EMPL_ID field. In the DEPARTMENT table, the department number is the primary key and is stored in the DEPT_NO field. The department number is also stored in a field in the EMPLOYEE table - the DEPT field. The department number field links the EMPLOYEE...
