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.
BEGIN Parameter Description in pl sql: BEGIN: This keyword signals the beginning of the executable section of a PL/SQL block, that contains executable statements. The execut
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
Using LIMIT For nested tables, that have no maximum size, the LIMIT returns NULL. For varrays, the LIMIT returns the maximum number of elements that a varray can have (that yo
Implicit Cursors The Oracle implicitly opens a cursor to process each SQL statement not related with an explicitly declared cursor. The PL/SQL lets you refer to the most recen
Example of WRAP Operator - SQL The effect of Example can be obtained in SQL but note that one needs to write down not only the names of the columns being wrapped but also the
Using EXTEND To enlarge the size of a collection, use EXTEND. This process has 3 forms. The EXTEND appends one null element to a collection. And the EXTEND(n) appends n null e
Lightweight system to provide and take info from workers in the field and office, have basic design outlined already just require build and implementation Desired Skills CSS,
Cursor Variables As Parameters You can declare the cursor variables as the formal parameters of the functions and procedures. In the illustration below, you define the REF CUR
Project Description: I want to write some SQL statements. The things I need are between pages 5-7. The only problem is that i want it till tomorrow. Skills required is SQL
Parameter Modes To define the behavior of formal parameters you use the parameter modes. The 3 parameter modes, IN, OUT, & IN OUT, can be used with any subprogram. Though, a
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