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

Some varray examples-manipulating collections, Some Varray Examples In S...

Some Varray Examples In SQL Plus, assume that you define an object type Project, as described below: SQL> CREATE TYPE Project AS OBJECT ( 2 project_no NUMBER(2), 3 title VARCHA

Processing transactions, Processing Transactions This part describes ho...

Processing Transactions This part describes how to do the transaction processing. You learn the fundamental techniques that safeguard the consistency of your database, involvin

Rollback behavior - bulk bind performance improvement, Rollback Behavior ...

Rollback Behavior When a FORALL statement fails, the database changes are rolled back to an implicit savepoint marked before each of the SQL statement execution. The Changes t

Running the pl/sql wrapper, Running the PL/SQL Wrapper To run the PL/SQ...

Running the PL/SQL Wrapper To run the PL/SQL Wrapper, go through the wrap command at your operating system prompt by using the syntax as shown: wrap iname=input_file [oname=

Sql cursor - syntax, SQL Cursor   The Oracle implicitly opens a cursor...

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

Effects of null for table expression, Effects of NULL for Table Expression ...

Effects of NULL for Table Expression Here's an important distinction between expressions denoting tables and expressions denoting multisets of rows: a table expression cannot

Keyword and parameter description - if statement, Keyword and Parameter Des...

Keyword and Parameter Description: boolean_expression: This is an expression which results the Boolean value TRUE, FALSE, & NULL. It is related with a series of statement

Sql functions, SQL Functions The PL/SQL uses all the SQL functions invo...

SQL Functions The PL/SQL uses all the SQL functions involving the following aggregate functions that summarize the whole columns of the Oracle data: GROUPING, AVG, COUNT, STDDE

Triggers, At times, customers make mistakes in submitting their orders and ...

At times, customers make mistakes in submitting their orders and call to cancel the order. Brewbean’s wants to create a trigger that automatically updates the stock level of all pr

Referencing records, Referencing Records Unlike the elements in a coll...

Referencing Records Unlike the elements in a collection, that are accessed using subscripts, the fields in a record are accessed by name. To reference an individual field, you

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