'Employee' with structure as ID, name, Address, Phone, Deptno
'Department' with structure as Deptno, Dname
_____ is used to represent the relationship between two relations Employee and Department.
Understanding Database Relationships: Employee and Department Tables
The question asks about the specific database concept used to link two different tables, specifically the 'Employee' table and the 'Department' table. We are given the structures of these tables:
- Employee Table: Contains columns like ID, name, Address, Phone, and Deptno.
- Department Table: Contains columns like Deptno and Dname.
The common column, 'Deptno', present in both tables is the key to establishing a connection or relationship between an employee and their respective department.
Database Keys Explained
Let's look at the different types of keys mentioned in the options to understand why one is correct:
- Primary Key: A column (or set of columns) that uniquely identifies each record within a table. For example, 'ID' in the Employee table is likely a primary key. 'Deptno' might be the primary key in the Department table.
- Candidate Key: Any column or set of columns that *could* serve as a primary key because it uniquely identifies records. Both 'ID' and potentially 'Deptno' (if unique in Employee) could be candidate keys for the Employee table.
- Alternate Key: A candidate key that was not chosen as the primary key. If 'Deptno' uniquely identified employees but 'ID' was chosen as the primary key, then 'Deptno' would be an alternate key.
- Foreign Key: A column (or set of columns) in one table that refers to the primary key (or another unique key) in another table. It creates a link between the two tables and ensures referential integrity (meaning you can't have an employee assigned to a department that doesn't exist).
Identifying the Linking Mechanism
In this scenario, the 'Deptno' column in the 'Employee' table points to the 'Deptno' in the 'Department' table. This is exactly the function of a Foreign Key. The 'Deptno' in the Employee table is referencing the primary key ('Deptno') of the Department table, thereby representing the relationship: each employee belongs to a specific department.
Therefore, the Foreign Key is used to represent the relationship between the Employee and Department relations.
Important Questions from Miscellaneous
A stone is thrown horizontally from the top of a 20 m high building with a speed of 12 m/s. It hits the ground at a distance R from the building. Taking g = 10 m/s2 and neglecting air resistance will give :
A mass is attached to a spring that hangs vertically. The extension produced in the spring is 6 cm on Earth. The acceleration due to gravity on the surface of the Moon is one-sixth of its value on the surface of the Earth. The extension of the spring on the Moon would be:
Directions: Each item in this section consists of a sentence with an underlined word followed by four words (a), (b), (c), and (d). Select the option that is opposite in meaning to the underlined word and mark your response in your Answer Sheet accordingly.
The deluge affected the population.The major source of vitamins and minerals for vegetarians is
Which of the following statements about the Deccan Riots Commission is/are correct?
1. The Commission did not hold enquiries in the districts which were not affected.
2. The Commission did record the statements of ryots, sahukars and eye-witnesses.
Select the correct answer using the code given below:
