Database-Oracle [3i Infotech Placement]: Sample Questions 77 - 78 of 132

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Question 77

Oracle

Question

MCQ▾

Is it possible to modify a Datatype of a column when column contains data?

Choices

Choice (4)

a.

No

b.

Yes

c.

Question does not provide sufficient data or is vague

d.

None of the above

Answer

a.

Explanation

  • No, it is not always possible to modify a datatype of a column when column contains data.
  • If the table is empty or the column contains null values, we can change the column to any datatype.
  • However, we can change the datatype of a column to a compatible data type for example an INT can be changed to a FLOAT.

ALTER TABLE

  • Alter table changes column datatype or renames a column.
  • Used to add, modify, or delete columns in a table.
  • Statement is also used to rename a table.

Syntax:

ALTER TABLE table_name

ADD column_name column-defination.

Question 78

Oracle
Edit

Write in Short

Short Answer▾

Name two utilities that Oracle provides, which are use for backup and recovery.

Explanation

  • Along with the RDBMS software, Oracle provides two utilities to back up and restore the database- Export and Import.
  • The Export utility dumps the definitions and data for the specified part of the database to an operating system binary file.
  • The Import utility reads the file produced by an export, recreates the definitions of objects, and inserts the data.
  • Used as a means of backing up and recovering the database, all the changes made to the database cannot be recovered since the export was performed.

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