Tag: SQL

What is the difference between Stored Procedure and Trigger in SQL

In this article, we will see the difference between Stored Procedure and Trigger in SQL. Following are the main differences between Stored Procedure and Trigger:

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Stored Procedure Trigger
Store Procedures are invoked explicitly Triggers are invoked implicitly
Stored procedure is a user defined piece of code which may return a value (making it a function) that is invoked by calling it explicitly. A trigger is a stored procedure that runs automatically when various events happen (eg update, insert, delete).

Difference between Stored procedure and Function in SQL

Following are the main differences between Stored procedure and Function in SQL.

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Stored Procedure Function
Stored procedure may or may not return values A Function must return a value
Stored procedures can have input/output parameters Functions can have only input parameters
Stored Procedure may take 0 to n input parameters For a Function it is mandatory to take one input parameter

What is the difference between union and join

Following are the differences between union and join in relational database engines.
A union returns the results of two different queries as a single recordset and A join allows you to relate similar data in different tables.

UNION JOIN
UNION puts lines from queries after each other, JOIN makes a cartesian product and subsets it
Union Operation is combined result of the Vertical Aggregate of the rows JOIN Operation is combined result of the Horizontal Aggregate of the Columns
Union combines rows JOIN links the rows
Performed only on two similar structures Performed only on two dissimilar structures also
A union returns the results of two different queries as a single recordset. A join allows you to relate similar data in different tables.

Visual depiction of a join. Table A and B’s columns are combined into a single result:

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