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

Explicit cursors, Explicit Cursors The set of rows returned by the que...

Explicit Cursors The set of rows returned by the query can include zero, one, or multiple rows, depending on how many rows meet your search criteria. Whenever a query returns

Overview of control structures-comparison operators, Overview of control st...

Overview of control structures According to the structure theorem, any computer program can be written by using the basic control structures as shown in figure below. They can b

Update statement - syntax, UPDATE Statement   The UPDATE statement tra...

UPDATE Statement   The UPDATE statement transforms the values of the specified columns in one or more rows in the table or view. Syntax:

Biochemical origin of life - modern concept, BIOCHE M ICA L ORIGIN OF LI...

BIOCHE M ICA L ORIGIN OF LIFE - It is generally agreed by astronomers, geologists and biologists that the earth is approximately 4500-5000 million years old. It is an

Maintain an audit trail of product table changes, The accuracy of product t...

The accuracy of product table data is critical and the Brwebean's. owner wants to have an audit file that contains information regarding all DML activity on the BB_PRODUCT table. T

Advantages of wrapping, Advantages of Wrapping   The PL/SQL Wrapper co...

Advantages of Wrapping   The PL/SQL Wrapper convert the PL/SQL source code into a transitional form of the object code. By hiding the application internals, the Wrapper secure

Object types and collections - performance of application, Use Object Types...

Use Object Types and Collections The Collection types and object types increase your efficiency by allowing for the realistic data modeling. The Complex real-world entities an

Best practices/Data Warhousing, What are 3 good practices of modeling and/o...

What are 3 good practices of modeling and/or implementing data warehouses?

Other monadic - sql, Other monadic - SQL In 2VL there are just 4 (2 2 ...

Other monadic - SQL In 2VL there are just 4 (2 2 ) monadic operators, of which negation is really the only "useful" one. When a third truth value is introduced we have 27 (3 3

Library system, Hi,am developing a library system and relating all the tabl...

Hi,am developing a library system and relating all the table is somehow complex,could you kindly assist me

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