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!
Using RENAME in combination with JOIN - SQL
Example gives pairs of ids of students having the same name, by joining two renamings of IS_CALLED. Example gives an equivalent expression in SQL.
Example: Renaming and joining
Student Sid1 is called Name and so is student Sid2
SELECT *
FROM (SELECT StudentId AS Sid1, Name FROM IS_CALLED)
NATURAL JOIN
(SELECT StudentId AS Sid2, Name FROM IS_CALLED)
As before, the result sagely tells us that student S1 (Anne) has the same name as herself and also shows two pairings of S1 with S5 (both named Boris). The pairing of a student id with itself can be avoided by adding WHERE Sid1 < > Sid2 to the WHERE clause. The duplicate pairings can further be avoided by using < instead of < > in this addition, but that trick assumes that an ordering is defined for type SID, which is not necessarily the case.
Equivalences & Rewrite Rules: If notice that as well as allowing us to prove trivial theorems, and tautologies enable us to establish that certain sentences are saying the sam
Package STANDARD package named STANDARD defines the PL/SQL atmosphere. The package specification globally declares the exceptions, types, and subprograms that are available a
Question: Consider the following relations (primary keys are underlined): AUTHOR (ANo, aname, address, speciality) PUBLISHER (PNo, pname, Location) BOOK (BNo, Title, ISBN,
Cursors To execute the multi-row query, the Oracle opens an unnamed work region which stores the processing information. The cursor names the work region, access the informa
Parameter Default Values As the illustration below shows, you can initialize the IN parameters to the default values. In that way, you can pass various numbers of actual par
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
Effects of NULL The numeric variable X, perhaps of type INTEGER, might be assigned NULL. In that case the result of evaluating X + 1 is NULL, and so SET Y = X + 1 assigns NULL
DECLARE : This keyword signals the beginning of the declarative section of the PL/SQL block, that contains local declarations. The Items declared locally exist only within the
What Is a Package? The package is a schema object that group logically related PL/SQL items, types, and subprograms. The Packages usually have 2 parts, a specification & a bo
Data Types in SQL - Timestamp TIMESTAMP for values representing points in time on a specified uniform scale. DATE is used for timestamps on a scale of one day, such as DATE '2
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