3i Infotech Papers: Sample Questions 575 - 576 of 1245

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Question number: 575

» Database » MySQL

Essay Question▾

Describe in Detail

What command is used to create a table by copying the structure of another table?

Explanation

Define Create table as select

Define Create Table as Select

Define Create table as select

  • CREATE TABLE…. AS SELECT command creates a table by copying the structure of another table.

  • If WHERE clause of the SELECT command contains a FALSE statement- the statement only copies structure:

    CREATE TABLE NEWTABLE AS SELECT * FROM EXISTING TABLE WHERE 1 = 2;

  • The where condition is true, then all the rows satisfying the condition will be copied to the new table.

  • SQL SELECT statement retrieves data from a table in the database.

  • Query may retrieve information from specified columns or from all rows in the table.

Question number: 576

» Database » Oracle

Essay Question▾

Describe in Detail

What is Oracle Block? Can two Oracle Blocks have the same address?

Explanation

Given Oracle data block and operating system blocks.

Given Oracle Data Block and Operating System Blocks.

Given Oracle data block and operating system blocks.

  • Oracle “formats” the database files into a number of Oracle blocks when they are first created making it easier for the RDBMS software to manage the files and easier to read data into the memory areas

  • The block size should be a multiple of the operating system block size.

  • Regardless of the block size, the entire block is not available for holding data; Oracle takes up some space to manage the contents of the block.

  • This block header has a minimum size, but it can grow.

  • These Oracle blocks are the smallest unit of storage.

  • Increasing the Oracle block size can improve performance, but it should be done only when the database is first created.

  • Two blocks can have the same block address if they are in different database files.