Database [3i Infotech Placement]: Sample Questions 289 - 291 of 294

Glide to success with Doorsteptutor material for competitive exams : get questions, notes, tests, video lectures and more- for all subjects of your exam.

Question 289

Database
Edit

Describe in Detail

Essay▾

State the difference between a “where” clause and a “having” clause.

Explanation

Difference between a Where Clause and a Having Clause
where clausehaving clause
  • A where clause is used is filter records from a result
  • A having clause is used to filter values from a group.
  • Where clause cannot be used with aggregates
  • Having clause can be used with aggregates.
  • Where clause can be used with Select, Update and Delete Statement
  • Having clause can be used only with Select statement.
  • Where clause is used on the individual record.
  • Having clause in conjunction with group by clause work on the record sets.
  • The where clause selects rows before grouping
  • The having clause cannot be used without the group by clause.

Question 290

Database
Edit

Write in Short

Short Answer▾

How will you copy the structure of a table without copying the data?

Explanation

There is one method for copying the structure of table without copying the data is create table NEWTable AS select ⚹ from OLDTABLE where 1 = 2

Question 291

Database
Edit

Write in Short

Short Answer▾

What is Lossless join property?

Explanation

Understanding of Lossless Join
  • It guarantees that the spurious tuple generation does not occur with respect to relation schemas after decomposition.
  • If we decompose a relation R into relations R1 and R2,
    • Decomposition is lossy if
    • Decomposition is lossless if

Developed by: