SQL Queries for Interview Questions

The following command is used to identify the version of SQL Server:

Select SERVERPROPERTY(‘productversion’)

Inner Join basically gives us those records that have matching values in two tables.

Let us suppose that we have two tables, Table A and Table B. When we apply Inner Join on these two tables, we will get only those records that are common to both Table A and Table B.

Syntax:

SELECT columns

FROM table1

INNER JOIN table2

ON table1.column_x=table2.column_y;

Example:

select * from employee

select * from department

Output:

Now, we will apply Inner Join to both these tables, where the e_dept column in the employee table is equal to the d_name column of the department table.

Syntax:

select employee.e_name, employee.e_dept, department.d_name, department.d_location

from employee inner join department

on

employee.e_dept=department.d_name

Output:

After applying Inner Join, we have only those records where the departments match in both tables. As we can see, the matched departments are Support, Analytics, and Sales.

Ans:

• First Normal Form (1 NF): It avoids data duplication in a table. It creates a specific table for the related data and uses the primary key to identify the data.
• Second Normal Form (2 NF): It creates separate tables for the group of data that belongs to multiple records. The tables are linked with foreign keys.
• Third Normal Form (3 NF): It eliminates the fields that are not related to keys
• Boyce Codd normal form /Fourth Normal form (BCNF or 4NF): It should be in the form of the 3 NF. Also, there shouldn’t be any multi-valued dependencies.