Use of count in sql, PL-SQL Programming

Assignment Help:

Use of COUNT in SQL

It describes and discusses various general methods of expressing constraints, eventually noting that support for "=" with relation operands is sufficient for completeness. It also notes that every constraint can be expressed as an invocation of IS_EMPTY, where IS_EMPTY(r) is equivalent to r { } = TABLE_DUM. First, though, it gives Example, showing how to use COUNT to test a relation for emptiness. Example here is a direct translation of that one into SQL.

Example: Testing for absence of counterexamples.

CREATE ASSERTION Must_be_enrolled_to_take_exam

CHECK ((SELECT COUNT (*)

FROM EXAM_MARK

WHERE (Student_Id, CourseId ) NOT IN

(SELECT Student_Id, CourseId

FROM IS_ENROLLED_ON ) )

= 0);


Related Discussions:- Use of count in sql

Use of count in sql, Use of COUNT in SQL It describes and discusses va...

Use of COUNT in SQL It describes and discusses various general methods of expressing constraints, eventually noting that support for "=" with relation operands is sufficient f

Using savepoints, Using Savepoints The scope of the savepoint is a tra...

Using Savepoints The scope of the savepoint is a transaction in which it is defined. The Savepoints defined in the major transaction are not related to the savepoints defined

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

Components of an object type - attributes in pl/sql, Attributes: Just ...

Attributes: Just similar to variable, an attribute is declared with a name and datatype. The name should be exclusive within the object type. The datatype can be any Oracle ty

Using operator deref - manipulating objects in pl sql, Using Operator DEREF...

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

Example of add constraint in sql, Example of ADD CONSTRAINT in SQL Exa...

Example of ADD CONSTRAINT in SQL Example: Alternative formulation for MAX_ENROLMENTS ALTER TABLE IS_ENROLLED_ON ADD CONSTRAINT MAX_ENROLMENTS CHECK ((SELECT COUNT (*)

How to use the explain plan for statement, Using the student and faculty ta...

Using the student and faculty tables create a select query that outputs all students for a specific advisor. Generate the execution plan, select out the explain plan . Create an

Subprograms, Subprograms The PL/SQL has two types of subprograms known ...

Subprograms The PL/SQL has two types of subprograms known as the procedures and functions that can take parameters and be invoked. As the following example represents, a subp

Create a procedure to tax calculation task, Complete the following steps to...

Complete the following steps to create a procedure to calculate the tax on an order. The BB_TAX table contains the states that require taxes to be submitted for Internet sales. If

Data types in sql, Data Types in SQL SQL's concept does not differ sig...

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

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