Example of cast operator - sql, PL-SQL Programming

Assignment Help:

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 gives NULL, instead of zero, for the courses whose exams nobody sat. That problem can be addressed by using COALESCE, as shown in Example.

Example: Give the total of marks for 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 SUM (Mark)

FROM TABLE(ER (ExamResult)) AS t) AS n

FROM C_ER

Explanation

COALESCE((SELECT SUM(Mark) FROM TABLE(ER(ExamResult)) AS t),0) yields the value of the scalar subquery whenever ExamResult is nonempty, otherwise zero. SQL's COALESCE is an n-adic operator that takes a commalist of expressions of the same declared type and yields the result of the first of those expressions, in the order in which they are written, that does not evaluate to NULL. When there is no such operand, it yields NULL anyway, of course.

Related Discussions:- Example of cast operator - sql

Using default-declarations in sql, Using DEFAULT You can use the keyword...

Using DEFAULT You can use the keyword DEFAULT rather than that of the assignment operator to initialize the variables. For e.g. the declaration blood_type CHAR := ’O’; it can b

Example of alternative formulation as a table constraint, Example of Altern...

Example of Alternative formulation as a table constraint Example: Alternative formulation as a table constraint ALTER TABLE EXAM_MARK ADD CONSTRAINT Must_be_enrolled_to_

Iterative control: loop statement, Iterative Control: LOOP Statements T...

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

Do you know anyone that can do this type of coding or not?, Task 2 [12 mark...

Task 2 [12 marks] Write the package body for the following package specification (the detailed description of each function and procedure is provided in the appendix below). Place

Sql, Write a query to find academics that are authors and that have only ev...

Write a query to find academics that are authors and that have only ever coauthored papers with authors from institutes in the same state as their own. List their academic number,

Build a purchases report that matches the general ledger, Great Plains (Mic...

Great Plains (Microsoft Dynamics) Purchases Report Project Description: I want to build a purchases report that matches the General Ledger. presently, when I join the PM20

%notfound - implicit cursor attributes, %NOTFOUND The %NOTFOUND is the...

%NOTFOUND The %NOTFOUND is the logical opposite of the %FOUND. The %NOTFOUND yields TRUE when an INSERT, UPDATE, or DELETE statement affected no rows, or the SELECT INTO state

Pl sql code to declare cursors with parameter, Write a pl/sql block that de...

Write a pl/sql block that declares and uses cursors with parameters. In a loop, use a cursor to retrieve the department number and the department name from the departments table

Explicit cursor attributes, Explicit Cursor Attributes The cursor varia...

Explicit Cursor Attributes The cursor variable or each cursor has four attributes: %FOUND, %ISOPEN, %ROWCOUNT, and %NOTFOUND. When appended to the cursor or cursor variable, th

Example of foreign key constraint - sql, Example of Foreign Key Constraint ...

Example of Foreign Key Constraint Example: Alternative formulation for 6.3 as a foreign key constraint ALTER TABLE EXAM_MARK ADD CONSTRAINT Must_be_enrolled_to_take_exam

Write Your Message!

Name

Email id

Message

Verfication Code

User Account

All Pages