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

Sqls counterpart of the key words, SQLs counterpart of the key words: ...

SQLs counterpart of the key words: The text from the opening parenthesis to the end of the fourth line specifies the declared type of the table, meaning that every table ever

Recursion, Recursion The Recursion is a powerful method for simplify th...

Recursion The Recursion is a powerful method for simplify the design of the algorithms. Principally, the recursion means the self-reference. In the recursive mathematical serie

Query optimization, 1.( /5 marks) Suppose that a B+-tree index with the sea...

1.( /5 marks) Suppose that a B+-tree index with the search key (dept_name, building) is available on relation department. What would be the best way to handle the following selecti

Select query, Query: SELECT * FROM EMPLOYEE1; Select 5 columns and ...

Query: SELECT * FROM EMPLOYEE1; Select 5 columns and all rows from one table Query: SELECT C_ID, COMPANY, BUILDING, DEPARTMENT, BRANCH FROM CONTRACT;

I want online credit application website, Project Description: We organi...

Project Description: We organize an online system called ACPAS we have created a project called EVO that can be use by our customers to integrate their web sites with the Acpas

Initializing objects in pl sql, Initializing Objects: Till you initiali...

Initializing Objects: Till you initialize an object by calling the constructor for its object type, the object is automatically null. That is, the object itself is null, not me

Theory of biogenesis, THEORY OF BIOGENESIS - This theory explains th...

THEORY OF BIOGENESIS - This theory explains that the existing living organisms originated from pre-existing living beings not from non living entities. This concept of or

Cursor attributes in pl sql, Cursor Attributes   The Cursors and curso...

Cursor Attributes   The Cursors and cursor variables have 4 attributes which give you helpful information about the execution of a data manipulation statement. Syntax:

Use of table expressions - expressing constraint conditions, Use of Table E...

Use of Table Expressions - Expressing Constraint Conditions With the exception of key constraints, the examples in the theory book all explicitly reference at least one relvar

Functions in pl/sql, Functions   The function is a subprogram that cal...

Functions   The function is a subprogram that calculates a value. The Functions and procedures are structured similar, except that the functions have a RETURN clause. You can

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