Interview Questions.

Question 1. What Is A Foreign Key?

Answer :

A foreign secret is one desk which can be related to the primary key of every other desk. Relationship needs to be created between two tables by means of referencing foreign key with the number one key of some other desk.

Question 2. What Is Normalization?

Answer :

Normalization is the procedure of minimizing redundancy and dependency by way of organizing fields and desk of a database. The most important aim of Normalization is to feature, delete or alter discipline that can be made in a unmarried desk.

SQL Server 2008 Interview Questions
Question 3. What Is Self-join?

Answer :

Self-be a part of is set to be query used to examine to itself. This is used to compare values in a column with other values within the same column inside the equal table. ALIAS ES may be used for the equal table comparison.

Question 4. What Is Sql Profiler?

Answer :

Microsoft SQL Server Profiler is a graphical consumer interface to SQL Trace for monitoring an instance of the Database Engine or Analysis Services. You can seize and store records about every event to a document or table to analyze later.

Use SQL Profiler to display best the activities in that you are fascinated.

If strains are becoming too big, you may filter them primarily based on the records you want, in order that simplest a subset of the occasion facts is accumulated. Monitoring too many activities provides overhead to the server and the monitoring manner and can motive the hint report or trace table to grow very large, specially whilst the monitoring method takes location over an extended time period.

SQL Server 2008 Tutorial
Question 5. How To Find Second Highest Salary Of An Employee?

Answer :

There are many ways to locate second maximum income of Employees in SQ. You can either use SQL Join or Subquery to clear up this problem.

Here is SQL question using Subquery :

Select MAX(Salary) from table1 WHERE Salary NOT IN ( select MAX(Salary) 

from table1 .

SQL Database Interview Questions
Question 6. What Is The Difference Between Truncate And Drop Statements?

Answer :

TRUNCATE removes all of the rows from the desk, and it can't be rolled lower back. DROP command removes a table from the database and operation can not be rolled again.

Question 7. What Are Aggregate And Scalar Functions?

Answer :

Aggregate features are used to evaluate mathematical calculation and go back unmarried values. This may be calculated from the columns in a table. Scalar features go back a single value based on the input value.

Example -.

Aggregate – max(), be counted – Calculated with appreciate to numeric.

Scalar – UCASE(), NOW() – Calculated with appreciate to strings.

SQL Database Tutorial MySQL Interview Questions
Question eight. Which Operator Is Used In Query For Pattern Matching?

Answer :

LIKE operator is used for sample matching, and it may be used as:

% – Matches zero or greater characters.
_(Underscore) – Matching exactly one man or woman.
Question 9. What Is A View?

Answer :

A view is a digital table which includes a subset of data contained in a desk. Views are not genuinely present, and it takes less space to keep. View may have statistics of one or greater tables blended, and it is depending on the relationship.

DB2 Using SQL Interview Questions
Question 10. What Is A Query?

Answer :

A DB question is a code written a good way to get the records back from the database. Query may be designed in the sort of manner that it matched with our expectation of the result set. Simply, a query to the Database.

MySQL Tutorial
Question 11. What Is Collation?

Answer :

Collation is defined as set of regulations that determine how individual records may be sorted and in comparison. This can be used to examine A and, different language characters and also depends on the width of the characters.
ASCII fee may be used to compare these man or woman information.

PostgreSQL Interview Questions