Describe and provide an example of an entity-relationship (E-R) diagram.
In our day to day database use, we need to identify data in database tables with the help of identifiers that may be present in other tables. To make these types of operations work, we need to establish dependencies and assign identifiers from one database to the data in other table. These dependencies are created in the form of E-R diagrams. In creating E-R diagrams, we assign foreign keys from one table to another table. These keys act as the fundamental ingredients in these relations. So for example when we have two tables related to different data about student, for example one table is about the personal information of a student and another table is about the academic record of the student, we can make a student Roll number column in the academic record table and assign it as a foreign key in the personal data table. Hence we can identify different attributes of a student from different tables with a single value i.e. student’s Roll number.