Database-MySQL [3i Infotech Placement]: Sample Questions 77 - 79 of 162

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Question 77

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Write in Short

Short Answer▾

What is an Entity?

Explanation

Entities with Example and Its Type
  • Entity set is a entities of the same type that share the same properties.
  • For example, a STUDENT entity may have a Name, Roll number, Class, Marks etc. where STUDENT is the entity and name roll number class marks are the attributes.

Question 78

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Describe in Detail

Essay▾

What is the difference between TRUNCATE and DELETE commands?

Explanation

Differentiate between the Truncate and Delete Commands
TRUNCATEDELETE
DDL commandDML command.
No use of where clauseWhere clause is used with DELETE to filter & delete specific records
Removes all rows from a table.Used to remove rows from a table based on WHERE condition.
Minimal logging in transaction log- faster.Maintains the log- slower than TRUNCATE.
Truncating a table requires ALTER permission.To delete we need DELETE permission.
Uses less transaction space than Delete statement.Uses more transaction space than Truncate statement.

Question 79

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Describe in Detail

Essay▾

How do you communicate with an RDBMS?

Explanation

Structure of a Relational Database
  • You can communicate RDBMS by structural query language (SQL) .
  • The SQL is used for inserting/modifying/deleting & retrieving data from Database.
  • You can also use SQL for Access controls & Administration.
  • SQL is classified into three categories, those categories are listed below.

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