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.
Many of the reports generated from the system calculate the total dollars in a shopper''s purchases. Follow these steps to create a function named TOT_PURCH_SF that accepts a shopp
Comparison Operators Usually, you use the comparison operators in the WHERE clause of a data manipulation statement to form the predicates, that compare one expression to anot
I need a query for PL/SQL, selecting names with cursor, goes down the list, assigns usernames (initials001) based on initials in the name. If two names have same initials the user
Role of Abstraction in pl/sql: The abstraction is a high-level description or model of a real-world entity. The Abstractions keep our daily lives convenient. They help us ca
Assigning and Comparing Collections One collection can be assigned to other by an SELECT, INSERT, UPDATE, or FETCH statement, an assignment statement, or by a subprogram call. A
Parameter and Keyword Description: procedure_name The user-defined procedure is declared by this construct. parameter_name: This identifies the formal parameter t
Data Types in SQL - Character CHARACTER or, synonymously, CHAR, for character strings. When this type is to be the declared type of something (e.g., a column), the permissible
Autonomous versus Nested Transactions Though an autonomous transaction is started by the other transaction, it is not a nested transaction for the reasons shown below: (i)
Using a Join on 2 tables, select all columns and all rows from the tables without the use of a Cartesian product. Query: SELECT * FROM EMPLOYEE1 JOIN CONTRACT ON EMPLOYEE
Loop Labels Like the PL/SQL blocks, loops can also be labeled. The label, an undeclared identifier enclosed by double angle brackets, should appear at the beginning of the LOOP
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