Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
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)
Example of GROUP BY and COLLECT Operator Example: Using GROUP BY and COLLECT to obtain C_ER2 SELECT CourseId, CAST ( COLLECT (ROW (StudentId, Mark)) AS ROW (Studen
This task involves developing some functions that extract data from an SQL database. The scenario is that a company which owns an online vehicle search website wants to generate so
Iterative Control: LOOP Statements The LOOP statement executes a series of statements multiple times. There are 3 forms of LOOP statements: LOOP, WHILE-LOOP, & FOR-LOOP. LOOP
Keyword &Parameter Description: index_name: This is an undeclared identifier which can be referenced only within the FORALL statement and only as the collection subscript
Conditionals - SQL At first sight SQL does not appear to have a single operator for expressing logical implication. In this respect it would be in common with most programming
Relational Operators The relational operators permit you to compare randomly complex expressions. The list below provides the meaning of each operator:
Assigning and Comparing Collections One collection can be assigned to other by an SELECT, INSERT, UPDATE, or FETCH statement, an assignment statement, or by a subprogram call. A
Definition of CROSS JOIN - SQL Let s = t1 CROSS JOIN t2, where t1 and t2 are table expressions optionally accompanied by range variables. Then: Note: Here T denotes Table
In Packages The Forward declarations also group logically related subprograms in the package. The subprogram specifications go in the package specification, & the subprogram b
Parameter and Keyword Description: table_reference: This keyword identifies the table or view that should be accessible when you execute the UPDATE statement, and for wh
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd