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

Pass the nulls to a dynamic sql, Pass the nulls to a dynamic SQL: Pas...

Pass the nulls to a dynamic SQL: Passing Nulls: Assume that you want to pass the nulls to a dynamic SQL statement. For illustration, you may write the EXECUTE IMMEDIATE

Using forall and bulk collect - bulk bind performance, Using FORALL and BUL...

Using FORALL and BULK COLLECT Together You can unite the BULK COLLECT clause with the FORALL statement, in that case, the SQL engine bulk-binds column values incrementally. In

Fetch statement - syntax, FETCH Statement The FETCH statement retrieve ...

FETCH Statement The FETCH statement retrieve rows of data one at a time from the result set of the multi-row query. The data is stored in fields or variables which correspond t

Components of an object type - parameter self, Parameter SELF in pl/sql ...

Parameter SELF in pl/sql The MEMBER methods recognize a built-in parameter named SELF that is an instance of the object type. Whether declared explicitly or implicitly, it is

Example of coalesce operator - sql, Example of COALESCE operator Examp...

Example of COALESCE operator Example: Give the total of marks for each exam (simplified solution) SELECT CourseId, COALESCE ((SELECT SUM (Mark) FROM EXAM_MARK AS EM

Methods in pl/sql, Methods: In normal, a method is a subprogram declar...

Methods: In normal, a method is a subprogram declared in an object type specification using the keyword MEMBER or STATIC. The method cannot have similar name as the object typ

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

Primary key - sql, Primary Key - SQL A PRIMARY KEY specification carri...

Primary Key - SQL A PRIMARY KEY specification carries an implicit NOT NULL constraint on each column of the specified key. When more than one key constraint is required, the k

I need sql - wp sql expert, I need SQL , WP SQL Expert Project Descripti...

I need SQL , WP SQL Expert Project Description: Expert required to modify WP SQL query. Skills required are MySQL, SQL, PHP, Wordpress

In operator-comparison operators, IN Operator The operator IN tests the ...

IN Operator The operator IN tests the set membership. This means "equal to any member of." The set may have nulls, but they are ignored. For illustration, the statement below do

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