Question: What is an index in SQL Server?
Answer: Index is responsible for arranging data physically to speed
up query performance. An index is a physical structure containing the pointers
of the data. We can create index one or more columns of the table. Creating a
relational index on the table is called the row-store index. It is either a
clustered or non-clustered index. There are two types of indexes.
1- Clustered index
2- Non-clustered index
3- A new index introduced in SQL Server 2014.
“Columnstore index.”
Question: What is a cursor in SQL Server?
Answer: Curser is responsible for manipulating data in a set on a row by
row basis. Actually, curser is the database object used by the application.
Question: Types of an index in SQL Server.
Answer: Types of the index is given below.
- Clustered
index
- Non-clustered
index
- Columnstore
index
Question: What are the constraints in SQL Server?
Answer: Constraints are the rules enforced on data columns on the
table. This ensures the accuracy and reliability of the data in the database.
Constraints define some conditions that restrict the column to remain true
while inserting or updating or deleting data in the column.
Question: Types of constraints in SQL Server?
Answer: Types of constraints is given below.
- NOT
NULL- This
constraint is responsible for a column to confirm that a column cannot
have a null value.
- DEFAULT
– This
constraint provides a default value when specified none for this column.
- UNIQUE- This constraint ensures that
each row for the column has a different value.
- PRIMARY
KEY- The
primary key constraint is a combination of a NOT NULL constraint and a
UNIQUE constraint. This constraint ensures that the specific column for a
table has a unique identity.
- FOREIGN
KEY- This
constraint responsible for uniquely identified rows/records in any other
database table.
- CHECK- The CHECK responsible for
enables a condition to check the value being entered into a record
