Database-MySQL [3i Infotech Placement]: Sample Questions 80 - 81 of 162

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Question 80

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Describe in Detail

Essay▾

What is SQL ⚹ Loader?

Explanation

The SQL Loader
  • SQL ⚹ loader is one of the Oracle tool which will be used to transfer the data from Flat-File to oracle Database table.
  • It has a powerful data-parsing engine that puts little limitation on the format of the data in the data file.

Use of SQL ⚹ Loader

  • Load data across a network if your data files are on a different system than the database.
  • Load data from multiple data files during the same load session.
  • Load data into multiple tables during the same load session.
  • Specify the character set of the data.
  • Selectively load data (you can load records based on the records՚ values) .
  • Manipulate the data before loading it, using SQL functions.
  • Generate unique sequential key values in specified columns.
  • Use the operating system՚s file system to access the data files.
  • Load data from disk, tape, or named pipe.
  • Generate sophisticated error reports, which greatly aid troubleshooting.
  • Load arbitrarily complex object-relational data.
  • Use secondary data files for loading LOBs and collections.

Question 81

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Describe in Detail

Essay▾

What is the use of the DROP option in the ALTER TABLE command?

Explanation

  • DROP option can be used to drop a col from table.
  • For example, ALTER TABLE tname DROP COLUMN colName.
  • The column may or not contain data.
  • The table must have at least one column remaining after being altered.
  • Once a column is dropped, it cannot be recovered.

Syntax:

ALTER TABLE table_name

DROP COLUMN column_name;

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