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!
Example of Using Aggregation on Nested Tables
Example: How many students sat each exam
WITH C_ER AS (SELECT CourseId, CAST (TABLE (SELECT DISTINCT StudentId, Mark FROM EXAM_MARK AS EM WHERE EM.CourseId = C.CourseId) AS ROW ( StudentId SID, Mark INTEGER ) MULTISET) AS ExamResult FROM COURSE AS C) SELECT CourseId, (SELECT COUNT (*) FROM TABLE (ER (ExamResult)) AS t) AS n FROM C_ER
Explanation
CREATE FUNCTION ER
(SM ROW ( StudentId SID, Mark INTEGER ) MULTISET )
RETURNS TABLE (StudentId SID, Mark INTEGER)
RETURN SM;
The type name TABLE ( StudentId SID, Mark INTEGER ) is actually just a synonym for ROW (StudentId SID, Mark INTEGER ) MULTISET). The misleading synonym is available only in a RETURNS clause and not as a parameter type, for example. So ER is actually a no-op, returning its input.
Dynamic Ranges The PL/SQL lets you determine the loop range dynamically at run time, as the example below shows: SELECT COUNT(empno) INTO emp_count FROM emp; FOR i IN 1..emp_cou
Closest Approximation to Relational Union - SQL Actually, just as SQL has several varieties of JOIN, it also has several varieties of UNION, none of which is equivalent to th
Cursor FOR Loops In most cases that need an explicit cursor, you can simplify the coding by using a cursor FOR loop rather of the OPEN, FETCH, and CLOSE statements. A cursor FO
Collection Methods: The collection method is a built-in function or procedure which operates on the collections and is called using the dot notation. The methods like the C
Defining Autonomous Transactions To define an autonomous transaction, you use the pragma (compiler directive) AUTONOMOUS_TRANSACTION. The pragma instructs the PL/SQL compiler
What Are Cursor Variables ? The Cursor variables are like C or Pascal pointers that hold the memory location (address) of some item rather of the item itself. Therefore, decl
Read-Only Operator (+) - SQL The term read-only operator to the mathematical term function. Here I just need to add that the SQL standard reserves the term function for read-
Adding Table Constraints ALTER TABLE ENROLMENT ADD CONSTRAINT NameNotNull CHECK (Name IS NOT NULL) ; ALTER TABLE ENROLMENT ADD CONSTRAINT PK_StudentId_CourseId PRIM
Using Operator DEREF: You cannot navigate through refs within the PL/SQL procedural statements. Rather than, you should use the operator DEREF in the SQL statement. The DEREF
Defining REF CURSOR Types To make cursor variables, you take 2 steps. At first, you define a REF CURSOR type, and then declare the cursor variables of that type. You can defin
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: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd