Oct 5, 2016

Interview Questions and answers - SQL Server Day 2

Question: What is an index in SQL Server?

Answer: Index is responsible to arrange data physically to speed up the query performance. Index is the physical structure containing to the pointers of the data. We can create index one or more columns of the table. Creating a relational index on table is called rowstore index it is either clustered or non-clustered index. There are two types of index

1-  Clustered index
2-  Non-clustered index
3-  A new index introduced in SQL Server 2014. “Columnstore index”

Question: What is curser in SQL Server?

Answer: Curser is responsible to manipulate data in a set on row by row basis. Actually curser is the database object used by application.

Question: Types of index in SQL Server.

Answer: Types of index is given below.
  1. Clustered index
  2. Non-clustered index
  3. Columnstore index

Question: What are constraints in SQL Server?

Answer: Constraints are the rules enforced on data columns on table. This ensures the accuracy and reliability of the data in the database. Constraints define some conditions that restricts the column to remain true while inserting or updating or deleting data in column.

Question: Types of constraints in SQL Server?

Answer: Types of constraints is given below.
  1. NOT NULL- This constraint is responsible for a column to confirm that a column cannot have a null value.
  2. DEFAULT – This constraint provides a default value when specified non for this column.
  3. UNIQUE- This constraint insure that each row for the column has different value.
  4. PRIMARY KEY- 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 have a unique identity.
  5. FOREIGN KEY- This constraints responsible to uniquely identified a rows/records in any another database table.
  6. CHECK- The CHECK responsible to enables a condition to check the value being entered into a record