Data Modeling Interview Questions
It is the process of creating data model for an information system. It is used to define and analyze data requirements needed to support the business process within the scope of corresponding information. Here are the top 25 Data Modeling interview questions for experienced and freshers.
1. What is Data Modeling?
Data model is a conceptual representation of Business Requirement (logic data model) or Data Base objects required for a database and very powerful in expressing and communicating the business requirements and database objects.
2. What does data model contain?
Logical Data Model Contain
Entry, Super Type, Sub Type, primary key, Alternate key, Inversion key Entry, Rule, Relationship, Definition, Business Rule, Entity, etc.
Physical Data Model Contain
Table, Column, Primary key Constraint, Unique Index, Non Unique Index, Check constraint, Default value, Foreign key, Comment etc.
3. What is a Table (entity)?
- Data stored in a form of rows and column is called as table.
- Each column has data type and based on the situation, integrity constraints are enforced on columns.
4. What is a column (attribute)?
Column also known as field is a vertical alignment of a data and constrains related to that columns.
5. What is a Row?
It is known as tuple or record is the horizontal alignment of the data.
6. What is index?
Index is imposed on column or set of columns for fastest retrieval of data.
7. What is a check constraint?
Check constraint is used to check range of values in a column.
8. What is a unique constraint?
Unique constraint is imposed on the column data to avoid duplicate values, but it will contain NULL values.
9. What is a foreign key ?
In relational databases, a foreign key is a field in one table which is used to uniquely identify a row of another table.
10. What are the important types of Relationships in a data model?
- Non – Identifying Relationship
- Self –Recursive Relationship
11. What is a sequence?
Sequence is a database object to generate unique number.
12. What is cardinality?
In a database, high cardinality means more unique values are stored in a column and vice versa.One to One, One to many, and many to many are different types of cardinalities.
13. What is a relational data modelling?
Visual representation of objects in a relational database is called as relational data modelling, table contains row and copy.
14. What is basic elements of ERD?
- There are three basic elements
- Entities which we seek information
- Attributes the data collect about the entities.
- Relationship provide the structure needed to draw information from multiple entities.
15. What is data model repository?
- A Data modelling repository is storage area, where metadata of a data model is stored.
- The data is stored in different from the software perspective, organization’s perspective and usage perspective.
- Repository can be stored any, where either in a data base or locally within any system.
16. What is De-Normalization?
- De- Normalization is a process of adding redundancy to the data.
- It helps us to quickly retrieve the information from the database.
17. What is OLTP data modelling?
- OLTP stands for online transactional processing.
- Data models are constructed for transactions is called OLTP data modelling.
18. What is a constraint? And its types?
- Constraint is a rule imposed on data.
- Different types of constraint:
- Primary key
- Not null
- Foreign key
- Composite foreign key
- Check constraint
19. What is reverse engineering in a data model?
- Reverse Engineering is a process useful for creating the data modes from database and scripts.
- In this tools have options to connect the database by which we can reverse engineer a database into a data model.
20. What is a composite foreign key constraint?
- Foreign key constraint is a column, that is used to establish and enforce a link between the data in two tables.
- It is defined as constraint create or modify a table.
21. What is a primary key constraint?
The primary key constraint is imposed on the column data to avoid null value and duplicate values.
22. What is a sequence?
It is a database object to generate unique number
23. What is self – recursive relationship?
Standalone column is a table will be connected to the primary key of the same table. It is called recursive relationship.
24. What is a composite foreign key constraint?
A group of columns in a foreign key, it is called as a composite foreign key constraint
25. What is forward engineering in a data model?
- It is a process by which DDL scripts are generated from the data model.
- Data modelling tools have options to create DDL Scripts by connecting with various databases.
- With its scripts and database can be created.