Relational Databases is a collection of tables. These tables are call Relations.
In the Departments table, Dept_Id is the primary key. In the Employee table, Dept_Id is called a foreign key. A foreign key is a column in one table that references a primary key in another table. The column can contain duplicate values. Along the line connecting the two tables, the 1 and 8 symbol indicate a one-to-many relationship. A particular Dept_Id (such as 4) occurs only once in the Departments table, but it can appear many times (or not at all) in the Employee table. At first, we will work with one table at a time. Later, we will show how to pull information from two related tables. (Gaddis 169)
Student Registration Database Example
Check and compare with your own database and analyze the relationship between tables(Entities)
How to write a table
First write the name of the table
Within the parentheses write all the collumns of the table