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

Effects of null for unique specification - sql, Effects of NULL for UNIQUE ...

Effects of NULL for UNIQUE Specification When a UNIQUE specification u for base table t includes a column c that is not subject to a NOT NULL constraint, the appearance of sev

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

Third step at defining type sid in sql, Third Step at defining type SID in ...

Third Step at defining type SID in SQL CREATE DOMAIN SID AS VARCHAR(5) CHECK ( VALUE IS NOT NULL AND SUBSTRING(VALUE FROM 1 FOR 1) = 'S' AND CAST('+'||SUBSTRING(VALUE

Use the returning clause -improve performance of application, Use the RETUR...

Use the RETURNING Clause Frequently, the application requires information about the row affected by a SQL operation, for illustration, to produce a report or take a subsequent

Renaming columns - sql, Renaming Columns - SQL SQL has no direct count...

Renaming Columns - SQL SQL has no direct counterpart of RENAME. To derive the table on the right in Figure 4.4 from the table on the left, Tutorial D has IS_CALLED RENAME ( St

%rowtype - cursors, %ROWTYPE: This attribute gives a record type which ...

%ROWTYPE: This attribute gives a record type which represents a row in the database table or a row fetched from a formerly declared cursor. The Fields in the record and corresp

Database Management, Due to an increase in overhead costs, the buying price...

Due to an increase in overhead costs, the buying price of all items needs to be increased. Management wants to see a report before deciding how much each product will go up. Add to

Restriction in sql, Restriction in SQL Syntax: SELECT DISTINCT...

Restriction in SQL Syntax: SELECT DISTINCT StudentId FROM IS_CALLED WHERE Name = 'Boris' The WHERE clause operates on the result of the FROM clause in analogo

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

Declarations in sql-pl/sql, Declarations in SQL Your program stores value...

Declarations in SQL Your program stores values in the variables and constants. As the program executes, the value of the variables can change, but the values constants cannot.

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