Using rename in combination with join - sql, PL-SQL Programming

Assignment Help:

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.


Related Discussions:- Using rename in combination with join - sql

Sql is a database language, SQL Is a Database Language: The commands g...

SQL Is a Database Language: The commands given to a DBMS by an application are written in the database language of the DBMS. The term data sublanguage is sometimes used instea

Using prior and next - collection method, Using PRIOR and NEXT The PRI...

Using PRIOR and NEXT The PRIOR(n) returns the index number that precede index n in a collection. The NEXT(n) returns the index number which succeed the index n. If n has no pr

Goto statement - sequential control, GOTO Statement The GOTO statement b...

GOTO Statement The GOTO statement branches to a label unconditionally. The label must be exclusive within its scope and should precede an executable statement or a PL/SQL block.

Advantages of subprograms, Advantages of Subprograms The Subprograms g...

Advantages of Subprograms The Subprograms give extensibility; that is, tailor the PL/SQL language to suit your requirements. For illustration, if you require a procedure which

In packages - subprograms, In Packages The Forward declarations also g...

In Packages The Forward declarations also group logically related subprograms in the package. The subprogram specifications go in the package specification, & the subprogram b

Inserting objects in pl sql, Inserting Objects: You can use the INSERT...

Inserting Objects: You can use the INSERT statement to add objects to an object table. In the illustration below, you insert a Person object into the object table persons:

Declaring subprograms, Declaring Subprograms   You can declare subprog...

Declaring Subprograms   You can declare subprograms in any PL/SQL subprogram, block, or package. But, you should declare subprograms at the end of the declarative part after a

An active database in pl-sql, Consider the following set of database tables...

Consider the following set of database tables (same tables from Assignment 6-1). Please take note of foreign keys (most of them carry the same names as the corresponding primary ke

Sql operators, SQL Operators The PL/SQL uses all the SQL set, compariso...

SQL Operators The PL/SQL uses all the SQL set, comparison, and row operators in the SQL statements. This part briefly describes some of these operators.  1. Comparison Opera

Information hiding in pl/sql, Information Hiding   With the informatio...

Information Hiding   With the information hiding, you see only the details that are significant at a given level of algorithm and data structure design. The Information hiding

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