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!
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 the relational operator of that name. The closest approximation to relational union is illustrated in Example.
Example: SQL's closest approximation to relational union
SELECT StudentId
FROM IS_CALLED
WHERE Name = 'Devinder'
UNION DISTINCT CORRESPONDING
FROM IS_ENROLLED_ON
WHERE CourseId = 'C1'
The key word DISTINCT is optional and implied by default (somewhat curiously so, considering that its opposite, ALL, is the default option in the SELECT clause). It specifies that no row is to appear more than once in the result. Thus, there is never a need to include DISTINCT in either of the SELECT clauses, and this would be the case even if the WHERE clause were omitted from the specification of the second operand in Example, allowing the same StudentId value to appear more than once in that operand.
The key word CORRESPONDING specifies that operand columns are to be paired by name, just as in relational union.
Declaring Cursor Variables Once a REF CURSOR type is define by you, and then you can declare the cursor variables of that type in any PL/SQL block or subprogram. In the exampl
Description: Demonstrate your knowledge of PL/SQL programming by writing and thoroughly testing triggers and stored procedures associated with an e-commerce application that pr
TYPES OF EVOLUTION - Sequential evolution : Minor changes in the gene pool of a population from one generation to the next, with the resul
Why Use Cursor Variables ? Primarily, you use the cursor variables to pass the query result sets between the PL/SQL stored subprograms and different clients. Neither PL/SQL nor
Second Step at defining type SID in SQL CREATE TYPE SID AS VARCHAR(5) ; Explanation: TYPE SID announces that a type named SID is being defined to the system.
Example of Null operator - NiNo Rule If we wanted to make HIGHER_OF adhere to "NULL in, NULL out"-let's call it the NiNo rule-we would have to write something like what is sho
Raise_application_error - procedure of package DBMS_STANDARD , allows to issue an user_defined error messages by stored sub-program or database trigger.
%ROWTYPE: This attribute gives a record type which represents a row in the database table or a row fetched from a formerly declared cursor. The Fields in the record and corresp
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
Write a program to implement the inverted file shown in the slides (Simple Index file, LabelID file and Data file). Use the Avail_List to point at the deleted Label IDs so that th
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