Union and or - sql, PL-SQL Programming

Assignment Help:

UNION and OR - SQL

SQL supports UNION explicitly but differently from the way it supports JOIN explicitly. As we have seen, JOIN is used exclusively within the FROM clause, such that IS_CALLED NATURAL JOIN IS_ENROLLED_ON, for example, can be an element of that clause but cannot stand alone as a table expression. Instead, UNION always connects table expressions that can stand alone, these being:

  1. SELECT expressions
  2. TABLE tn, which is equivalent to SELECT * FROM tn, where tn is a table name
  3. VALUES expressions
  4. Invocations of UNION, INTERSECT and EXCEPT

Related Discussions:- Union and or - sql

Why use cursor variables, Why Use Cursor Variables ? Primarily, you use...

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

Product-specific packages in pl/sql, Product-specific Packages The Ora...

Product-specific Packages The Oracle and different Oracle tools are supplied with the product-specific packages which help you to build the PL/SQL-based applications. For illu

Difference between 9i & 10g, Difference between 9i & 10G When Oracle r...

Difference between 9i & 10G When Oracle releases any new databases then it are having some discrepancy with them. But 10G is having much difference than oracle 9i has. Oracle

Data types and representations, Data Types and Representations This ex...

Data Types and Representations This explains the concept possible representation, abbreviated possrep, and explains how these can be used in conjunction with constraints to de

Relational schema, query to Find the account numbers of all customers whose...

query to Find the account numbers of all customers whose balance is more than 10,000 $

Using forall statement - bulk bind performance improvement, Using the FORAL...

Using the FORALL Statement The keyword FORALL instruct the PL/SQL engine to bulk-bind input collections before sending them all to the SQL engine. Though the FORALL statement

Named notation, Named Notation The second procedure call uses the name...

Named Notation The second procedure call uses the named notation. An arrow (=>) serve as the relationship operator that associates the formal parameter to the left of the arro

Using not null-declarations in sql, Using NOT NULL Besides assigning an ...

Using NOT NULL Besides assigning an initial value, the declarations can impose the NOT NULL constraint, as the example below shows: acct_id INTEGER(4) NOT NULL := 9999; You ca

Null statement-sequential control, NULL Statement The NULL statement c...

NULL Statement The NULL statement clearly specifies in action; it does nothing other than to pass control to the next statement. It can, though, improve the readability. In a

Implicit rollbacks, Implicit Rollbacks Before execute the INSERT, UPDA...

Implicit Rollbacks Before execute the INSERT, UPDATE, or DELETE statement, the Oracle marks an implicit savepoint . When the statement fails, the Oracle rolls back to the save

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