Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Closest Approximation to Relational Union - SQL
Actually, just as SQL has several varieties of JOIN, it also has several varieties of UNION, none of which is equivalent to the relational operator of that name. The closest approximation to relational union is illustrated in Example.
Example: SQL's closest approximation to relational union
SELECT StudentId
FROM IS_CALLED
WHERE Name = 'Devinder'
UNION DISTINCT CORRESPONDING
FROM IS_ENROLLED_ON
WHERE CourseId = 'C1'
The key word DISTINCT is optional and implied by default (somewhat curiously so, considering that its opposite, ALL, is the default option in the SELECT clause). It specifies that no row is to appear more than once in the result. Thus, there is never a need to include DISTINCT in either of the SELECT clauses, and this would be the case even if the WHERE clause were omitted from the specification of the second operand in Example, allowing the same StudentId value to appear more than once in that operand.
The key word CORRESPONDING specifies that operand columns are to be paired by name, just as in relational union.
Parameter and Keyword Description: record_type_name: This identifies the user-defined type specifier that is used in the subsequent declarations of the records. NOT N
PITS Depressions in secondary cell wall is called pit. A pit present on the free cell wall surface without its partner is called Blind pit. It consists of 2 parts -
Example of Cast Operator So long as CAST is used as shown, we could obtain the total marks for each exam in similar fashion, using SUM (Mark) AS TotalMarks. However, this giv
Cursor Variables Similar to a cursor, cursor variable points to the current row in the result set of a multi-row query. But, dissimilar a cursor, a cursor variable can be opene
User-Defined Exceptions The PL/SQL defines the exceptions of your own. Dissimilar to the predefined exceptions, the user-defined exceptions should be declared and should be rai
BETWEEN and NOT BETWEEN Operator in SQL Example: Restricting exam marks to between 0 and 100 CREATE ASSERTION Marks_between_0_and_100 CHECK (NOT EXISTS (SELECT * FROM
Using Cursor Attributes To process the SQL data manipulation statements, the SQL engine must opens an implicit cursor named SQL. This cursor's attributes (%FOUND, %NOTFOUND, %
Authorize and fetch data from Instagram Project Description: Incorporate Instagram feed on mobile site platform: c#, ms sql, jquerymobile, jquery Web admin Author
EXECUTE IMMEDIATE Statement The EXECUTE IMMEDIATE statement prepare (parses) and instantly executes a dynamic SQL statement or an anonymous PL/SQL block. Syntax:
SQL Cursor The Oracle implicitly opens a cursor to process each SQL statement not related with an explicit cursor. The PL/SQL refers to the most current implicit cursor as t
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd