Multiple assignment - sql, PL-SQL Programming

Assignment Help:

Multiple Assignment- SQL

SQL supports multiple assignment to local variables and also applies multiple assignment semantics in SET clauses of UPDATE statements, but does not support multiple assignment in connection with updates on table targets. Thus, SQL has no counterpart to the theory book's Example, simultaneously deleting from both COURSE and IS_ENROLLED_ON. If we assume that there must be at least one enrolment for each course, and that students can enroll only on existing courses, deferred constraint checking has to be used, as shown in Example here.

Example: Withdrawing course C3 and deleting any enrolments on C3

Assume the definition of IS_ENROLLED_ON includes

CONSTRAINT Course_must_exist_for_enrolment

FOREIGN KEY (CourseId) REFERENCES COURSE ON DELETE NO ACTION

and the definition of COURSE includes

CONSTRAINT Enrolment_must_exist_for_course

CHECK ( CourseId IN (SELECT CourseId FROM IS_ENROLLED_ON)


Related Discussions:- Multiple assignment - sql

Manipulating individual elements - pl/sql, Manipulating Individual Elements...

Manipulating Individual Elements Faraway you have manipulated an entire collection. Within the SQL, to manipulate the individual elements of the collection, and then use the ope

Using trim - collection method, Using TRIM This process has two forms....

Using TRIM This process has two forms. The TRIM removes an element from the end of the collection. The TRIM(n) removes the n elements from the end of the collection. For e.g.

Join and and in sql, JOIN and AND in SQL In this Section is all about ...

JOIN and AND in SQL In this Section is all about one operator, JOIN. SQL's closest counterpart, NATURAL JOIN, has already been covered. Here we look at several other "join" op

Updating by insertion, Updating by insertion Syntax : INSERT IN...

Updating by insertion Syntax : INSERT INTO ENROLMENT VALUES (SID ('S4'), 'Devinder', CID ('C1'));

Cursors, What is Cursors how to use it in Real time application ?

What is Cursors how to use it in Real time application ?

Need fullcalendar modifications, Project Description: I am looking to ch...

Project Description: I am looking to change FullCalendar to add/delete sql server data when events are removed or dropped from Calendar. Events should only be included by dra

Functions in pl/sql, Functions   The function is a subprogram that cal...

Functions   The function is a subprogram that calculates a value. The Functions and procedures are structured similar, except that the functions have a RETURN clause. You can

Example of cast operator - sql, Example of Cast Operator So long as C...

Example of Cast Operator So long as CAST is used as shown, we could obtain the total marks for each exam in similar fashion, using SUM (Mark) AS TotalMarks. However, this giv

Mysql developer/programmer, Project Description: I want somebody who can...

Project Description: I want somebody who can help me with an idea that I have been working on for a few months now. The person will require extensive knowledge of warcraft 3 PvP

Exception handling, Exception handling In the PL/SQL, a warning or erro...

Exception handling In the PL/SQL, a warning or error condition is known as an exception. The Exceptions can be internally defined (by the run-time system) or user defined. The

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd