The correct answer is: B. Drag Foreign key of a table into Primary key of another table.
A foreign key is a column or columns in a table that refers to the primary key of another table. It is used to establish a relationship between two tables. The foreign key must contain the same data as the primary key of the other table.
For example, let’s say you have a table called Customers
and a table called Orders
. The Customers
table has a primary key called CustomerID
. The Orders
table has a foreign key called CustomerID
that refers to the CustomerID
column in the Customers
table. This means that each row in the Orders
table must have a value in the CustomerID
column that matches a value in the CustomerID
column in the Customers
table.
This relationship allows you to join the two tables together. For example, you could use a query to find all of the orders placed by a particular customer.
Option A is incorrect because you cannot drag a primary key into a foreign key. The primary key of a table is unique and cannot be duplicated. The foreign key, on the other hand, can contain duplicate values.
Option C is incorrect because you cannot drag any key of a table into any key of another table. The foreign key must refer to the primary key of the other table.
Option D is incorrect because only option B is correct.