Example of coalesce operator - sql, PL-SQL Programming

Assignment Help:

Example of COALESCE operator

Example: Give the total of marks for each exam (simplified solution)

SELECT CourseId,

COALESCE ((SELECT SUM (Mark)

FROM EXAM_MARK AS EM

WHERE EM.CourseId = C.CourseId ),

 0) AS TotalMark

FROM COURSE AS C

Explanation

  • The first operand to the invocation of COALESCE is a scalar subquery similar to Aggregate Operators. Recall the need to enclose the SELECT expression in parentheses, without which it would denote a table rather than a number.

Related Discussions:- Example of coalesce operator - sql

Enforce security in the database system, Question: (a) In the context o...

Question: (a) In the context of database security explain how the following database features help to enforce security in the database system: (i) Authorisation (ii) Access

Deriving predicates from predicates in sql, Deriving Predicates from Predic...

Deriving Predicates from Predicates in SQL The corresponding section in the theory book describes how predicates can be derived from predicates using (a) the logical connectiv

Aggregate operators sql, Aggregate Operators SQL Supports all of the a...

Aggregate Operators SQL Supports all of the aggregate operators mentioned in the theory book and many more besides. The syntax, however, involves an unusual trick that SQL cal

Testing triggers, Demonstrate your knowledge of PL/SQL programming by writi...

Demonstrate your knowledge of PL/SQL programming by writing and thoroughly testing triggers and stored procedures associated with an e-commerce application that provides security l

How bulk bind helps improvement in performance?, How Bulk Binds Improve Per...

How Bulk Binds Improve Performance The assigning of values to the PL/SQL variables in SQL statements is known as binding. The binding of the whole collection at once is know

Obtaining a natural join by specifying the common columns, Obtaining a natu...

Obtaining a natural join by specifying the common columns Synatax: SELECT * FROM IS_CALLED JOIN IS_ENROLLED_ON USING ( StudentId ) However, a named columns join doe

Cursor variables, Cursor Variables Similar to a cursor, cursor variable...

Cursor Variables Similar to a cursor, cursor variable points to the current row in the result set of a multi-row query. But, dissimilar a cursor, a cursor variable can be opene

Control structure, Control Structures The Control structures are the mo...

Control Structures The Control structures are the most important PL/SQL extension to the SQL. Not only does PL/SQL let you manipulate Oracle data, it lets you process the data

Write sql code that will create the writes table, Question: Consider th...

Question: Consider the following relations (primary keys are underlined): AUTHOR (ANo, aname, address, speciality) PUBLISHER (PNo, pname, Location) BOOK (BNo, Title, ISBN,

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