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SQL Interview Questions with Answers on Procedure, Trigger,

What is Stored Procedure?
A stored procedure is a named group of SQL statements that have been previously created and stored
in the server database. Stored procedures accept input parameters so that a single procedure can be
used over the network by several clients using different input data. And when the procedure is
modified, all clients automatically get the new version. Stored procedures reduce network traffic and
improve performance. Stored procedures can be used to help ensure the integrity of the database.
e.g. sp_helpdb, sp_renamedb, sp_depends etc.

What is Trigger?
A trigger is a SQL procedure that initiates an action when an event (INSERT, DELETE or UPDATE)
occurs. Triggers are stored in and managed by the DBMS.Triggers are used to maintain the referential
integrity of data by changing the data in a systematic fashion. A trigger cannot be called or executed;
the DBMS automatically fires the trigger as a result of a data modification to the associated table.
Triggers can be viewed as similar to stored procedures in that both consist of procedural logic that is
stored at the database level. Stored procedures, however, are not event-drive and are not attached to a
specific table as triggers are. Stored procedures are explicitly executed by invoking a CALL to the
procedure while triggers are implicitly executed. In addition, triggers can also execute stored
procedures.



Nested Trigger: A trigger can also contain INSERT, UPDATE and DELETE logic within itself, so when the
trigger is fired because of data modification it can also cause another data modification, thereby firing
another trigger. A trigger that contains data modification logic within itself is called a nested trigger.
What is View?
A simple view can be thought of as a subset of a table. It can be used for retrieving data, as well as
updating or deleting rows. Rows updated or deleted in the view are updated or deleted in the table the
view was created with. It should also be noted that as data in the original table changes, so does data
in the view, as views are the way to look at part of the original table. The results of using a view are
not permanently stored in the database. The data accessed through a view is actually constructed using
standard T-SQL select command and can come from one to many different base tables or even other
views.

Comments

  1. Hello Mate,


    Thank you! Thank you! Thank you! Your blog was a total game changer!


    I try to calculate MAT (Moving Annual Total) in my Finance Multi-dimensional cube with the below. It is not working or not calculating. But when I replace the Aggregate with Sum, it worked but wrong numbers. Need your help on finding the work around. I tried couple of options from internet

    Once again thanks for your
    tutorial.



    Thanks,
    Morgan

    ReplyDelete

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