First step at defining type sid in sql, PL-SQL Programming

Assignment Help:

First Step at defining type SID in SQL

CREATE TYPE SID AS ( C VARCHAR(5) ) ;

Explanation:

  1. TYPE SID announces that a type named SID is being defined to the system.
  2. AS ( C VARCHAR(5) ) defines SID as a structured type, whose values are represented as a structure consisting in this case of just a single attribute, named C, of type VARCHAR(5). (The term attribute here is not be confused with its use in relational theory.) The attribute definition C VARCHAR(5) causes an operator to come into existence that takes a value, of type SID and returns the value of the C component of s. The operator, SQL's counterpart of THE_C, is invoked using dot notation: s.C and is termed the observer function for the component C.

So-called constructor function, in this case a niladic operator named SID, is generated by the structure definition, such that SID() denotes the value of type SID whose only component is the "default value" for the attribute C, probably NULL. SID selector we need to use the so-called mutator function for the attribute C, which is also invoked using dot notation: SID().C('S1'). The mutator function takes a value of type SID as its left operand and a value of the declared type of C as its right operand (in parentheses). In general, if s is a value of type SID, then s.C('S1') denotes the SID value that is obtained from s by replacing its C component by the string 'S1'. If s had any other components (it doesn't, of course), they would be retained in s.C('S1'). By the way, don't be misled by the term "mutator": an SQL mutator function is a read-only operator.


Related Discussions:- First step at defining type sid in sql

Sql is a database language, SQL Is a Database Language: The commands g...

SQL Is a Database Language: The commands given to a DBMS by an application are written in the database language of the DBMS. The term data sublanguage is sometimes used instea

Oracle development , Write a stored procedure that accepts the post code in...

Write a stored procedure that accepts the post code in which the customer resides as the input parameter. The procedure should then use an explicit cursor to display comprehensive

Write a stored procedure, a. Create a table odetails_new. It has all the a...

a. Create a table odetails_new. It has all the attributes of odetails and an additional column called cost, whose values are the product of the quantity and price of the part bein

Delimiters, Delimiters A delimiter is a simple or compound symbol whi...

Delimiters A delimiter is a simple or compound symbol which has a special meaning to PL/SQL. For example, you use delimiters to symbolize an arithmetic operation like additio

Check constraints in sql, CHECK Constraints in SQL A CHECK constraint ...

CHECK Constraints in SQL A CHECK constraint is a table constraint defined using the key word CHECK, as already illustrated in several examples in this chapter. In particular,

Example of alternative formulation as a table constraint, Example of Altern...

Example of Alternative formulation as a table constraint Example: Alternative formulation as a table constraint ALTER TABLE EXAM_MARK ADD CONSTRAINT Must_be_enrolled_to_

Write sql code that will create the writes table, Question: Consider th...

Question: Consider the following relations (primary keys are underlined): AUTHOR (ANo, aname, address, speciality) PUBLISHER (PNo, pname, Location) BOOK (BNo, Title, ISBN,

Perform exception handling with user-defined errors, On occasion, some of B...

On occasion, some of Brewbean's customers mistakenly leave an item out of a basket already checked out, so they create a new basket containing the missing items. However, they requ

Truth tables , Truth Tables: However in propositional logic - here we ...

Truth Tables: However in propositional logic - here we are restricted to expressing sentences and where the propositions are true or false - so we can check where a particular

Varrays versus nested tables, Varrays versus Nested Tables The Nested ta...

Varrays versus Nested Tables The Nested tables are differing from varrays in the following ways: 1)  Varrays have a maximum size, while nested tables do not. 2)  Varrays are

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