Transaction log - Definition - Database

Q.  Which among the following comprises of a complete record of all activities responsible in affecting the database contents for a specific duration?
- Published on 26 Aug 15

a. Transaction log
b. Data manipulation language
c. Query language
d. Report writer

ANSWER: Transaction log
 

    Discussion

  • Nirja Shah   -Posted on 03 Nov 15
    Transaction logs
    - Transaction logs are a vital yet often overlooked component of database architecture.
    - They are often forgotten because they are not something actively maintained like the schema contained within a database.
    - In this article we’ll examine how transaction logs are used in Microsoft SQL Server, maintenance and potential problems with them, how they can be used to restore a database, and finally, optimizing them for performance.

    Query language
    - Data Query Language is used to extract data from the database. It doesn't modify any data in the database. It describes only one query: SELECT.

    DML
    - Data Manipulation Language (DML) statements are used for managing data within schema objects. Some examples:

    - SELECT - It retrieves data from the a database
    - INSERT - It inserts data into a table
    - UPDATE - It updates existing data within a table
    - DELETE - It deletes all records from a table, the space for the records remain
    - MERGE - The UPSERT operation (insert or update)
    - CALL - It calls a PL/SQL or Java subprogram
    - EXPLAIN PLAN - It explains the access path to data
    - LOCK TABLE - It controls concurrency

    Report writer
    - It is also known as a report generator, it is a program, which usually is a part of a database management system, that extracts information from one or more files and presents the information in a specified format.
    - Most of the report writers allows you to select the records that meet certain conditions and to display selected fields in rows and columns.
    - You can also format data into pie charts, bar charts, and other diagrams.
    - Once you have created a format for a report, you can save the format specifications in a file and continue reusing it for new data.

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