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)
FOR-LOOP While the number of iterations through a WHILE loop is unknown till the loop completes, then the number of iterations through a FOR loop is known before the loop is ent
Interesting properties of CROSS JOIN - SQL Compare these with the "interesting properties of JOIN", CROSS JOIN is associative but not commutative. Unlike JOIN and NATURAL JOI
Short-Circuit Evaluation When computing a logical expression, the PL/SQL uses short-circuit evaluation. That is, the PL/SQL stops computing the expression as soon as the result
Bulk Fetching The illustration below shows that you can bulk-fetch from a cursor into one or more collections: DECLARE TYPE NameTab IS TABLE OF emp.ename%TYPE; TYPE S
How Exceptions Are Raised By the run-time system, the internal exceptions are raised implicitly as are user-defined exceptions that you have related with an Oracle error number
a. Write an anonymous block that contains a PL/SQL function. Given an order number orderNo, the function will calculate the total number of the parts in the order. Then the anonym
Data Types in SQL SQL's concept does not differ significantly from that defined in the theory book, apart from that business concerning NULL. However, the theory book equates
SELECT INTO Statement The SELECT INTO statement retrieve data from one or more database tables, and then assigns the selected values to the variables or fields. Syntax:
Predefined Exceptions The internal exception is raised implicitly whenever your PL/SQL program exceeds a system-dependent limit or violates an Oracle rule. Each & every Oracle
Varrays versus Nested Tables The Nested tables are differing from varrays in the following ways: 1) Varrays have a maximum size, while nested tables do not. 2) Varrays are
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