Ans: Data definition language is used to define and manage all attributes and properties of a database.
Most DDL statements include following commands
CREATE
ALTER
DROP
Data Manipulation Language
Data manipulation language is used to select, insert, update, and delete data in the objects defined with DDL

Ans: The process of adding redundant data to get rid of complex join, in order to optimize database performance. This is done to speed up database access by moving from higher to lower form of normalization.

Ans:
Normalization is the way of organizing data in a database by removing redundancy and inconsistent dependency.
Database normalization has the rules to be followed while creating databases.
Each rule is called as normal form.
First Normal form states - Remove duplicate column and identify each set of related data with a primary key.
Second normal form - Create relationship between master and master detail tables using foreign key.
Third normal form - Remove the fields that do not depend on the primary key.
It is the process of organizing data into related table.
To normalize database, we divide database into tables and establish relationships between the tables.
It reduces redundancy. It is done to improve performance of query.

Ans:
One-to-one
One to one is implemented using single table by establishing relationship between same types of columns in a table. 
One-to-many
implemented using two tables with primary key and foreign key relationships.
Many-to-many
Implemented using a junction table.
The keys from both the tables form composite primary key of the junction table

Ans: The logical structure of databases is illustrated in the ER diagrams. These diagrams use symbols for representing different types of information. Boxes are used for representing entities. Rhombuses are used for representing relationships and ovals are used for representing attributes.
For a good database creation it is essential to have ER diagram. These diagrams follow top-down approach. To focus on how the database really works with all data flow and interactions, the best pattern is ER Diagrams

Ans: DBMS: A DBMS is a storage area that persist the data in files. To perform the database operations, the file should be in use. Relationship can be established between 2 files. There are limitations to store records in a single da...  

Ans: Fact tables are central tables in data warehousing. They contain the aggregate values that are used in business process. Dimension tables describe the attributes of the fact table.
Dimension Table: These tables are the end of the stars and contain the entity attributes. For example, one record for one customer is available in the customer dimension which interacted with the contact center and the every information is known to the customer.

Ans: Constraints enforce integrity of the database. Constraints can be of following types
Not Null
Check
Unique
Primary key
foreign key

Ans: Delete logs the deletion of each row whereas Truncate doesn't log deleted rows in the transaction log. This makes truncate command is bit faster than Delete command.

Ans: Triggers are similar to stored procedure except it is executed automatically when any operations are occurred on the table.