Infotech Sql Placement Papers - Infotech Sql Interview Questions and Answers
Q1. What Are Aggregate And Scalar Functions?
Aggregate functions are used to assess mathematical calculation and return single values. This may be calculated from the columns in a desk. Scalar features return a unmarried value based at the enter price.
Example -.
Aggregate – max(), remember – Calculated with admire to numeric.
Scalar – UCASE(), NOW() – Calculated with respect to strings.
Q2. What Is A Query?
A DB question is a code written so that it will get the statistics returned from the database. Query may be designed in any such manner that it matched with our expectation of the end result set. Simply, a question to the Database.
Q3. What Is Collation?
Collation is defined as set of regulations that decide how individual facts can be taken care of and in comparison. This may be used to compare A and, other language characters and also relies upon on the width of the characters.
ASCII value can be used to evaluate those character facts.
Q4. What Is The Difference Between Truncate And Drop Statements?
TRUNCATE eliminates all of the rows from the desk, and it cannot be rolled back. DROP command removes a table from the database and operation cannot be rolled again.
Q5. Which Operator Is Used In Query For Pattern Matching?
LIKE operator is used for pattern matching, and it may be used as:
% – Matches zero or more characters.
_(Underscore) – Matching precisely one person.
Q6. What Is A Foreign Key?
A overseas key is one desk which can be related to the primary key of every other desk. Relationship desires to be created among two tables with the aid of referencing overseas key with the number one key of another table.
Q7. What Is Normalization?
Normalization is the procedure of minimizing redundancy and dependency via organizing fields and table of a database. The foremost intention of Normalization is to feature, delete or alter discipline that can be made in a unmarried table.
Q8. What Is A View?
A view is a digital table which consists of a subset of records contained in a desk. Views aren't really gift, and it takes less area to keep. View can have facts of one or greater tables combined, and it's far relying on the relationship.
Q9. What Is Sql Profiler?
Microsoft SQL Server Profiler is a graphical person interface to SQL Trace for tracking an instance of the Database Engine or Analysis Services. You can seize and save facts approximately every occasion to a document or desk to analyze later.
Use SQL Profiler to monitor best the events in which you are fascinated.
If lines are becoming too massive, you can filter them primarily based on the facts you need, in order that simplest a subset of the occasion information is accumulated. Monitoring too many occasions provides overhead to the server and the tracking procedure and might motive the trace report or trace desk to grow very large, in particular while the tracking manner takes location over a long time frame.
Q10. What Is Self-join?
Self-be a part of is ready to be query used to evaluate to itself. This is used to evaluate values in a column with different values within the identical column inside the equal desk. ALIAS ES can be used for the equal table comparison.
Q11. How To Find Second Highest Salary Of An Employee?
There are many approaches to locate 2d highest salary of Employees in SQ. You can either use SQL Join or Subquery to remedy this trouble.
Here is SQL question the usage of Subquery :
Select MAX(Salary) from table1 WHERE Salary NOT IN ( select MAX(Salary)
from table1 .
