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

Assignment Help:

Third Step at defining type SID in SQL

CREATE DOMAIN SID AS VARCHAR(5)

CHECK ( VALUE IS NOT NULL AND

SUBSTRING(VALUE FROM 1 FOR 1) = 'S' AND

CAST('+'||SUBSTRING(VALUE FROM 2) AS INTEGER) >= 0 );

Explanation:

  1. DOMAIN SID announces that a domain named SID is being defined to the system.
  2. AS VARCHAR(5) specifies that values in domain SID are certain values of type VARCHAR(5).
  3. CHECK ( ... ) specifies a constraint defining exactly which values of type VARCHAR(5) are in the domain SID. Note that the key word VALUE, which is available only in domain constraints, refers (in this particular example) to an arbitrary value of type VARCHAR(5).
  4. VALUE IS NOT NULL specifies that the null value of type VARCHAR(5) is not a value in the domain. This is needed because the other conjuncts evaluate to UNKNOWN if VALUE is the null value and a domain constraint is deemed to be violated only when it evaluates to FALSE.
  5. SUBSTRING(VALUE FROM 1 FOR 1) = 'S' specifies that every value in the domain must begin with S. Note SQL's deliberate use of "noise" words in the invocation of SUBSTRING, the justification for which is to distinguish invocations of system-defined operators from those of user-defined ones.
  6. CAST('+'||SUBSTRING(VALUE FROM 2) AS INTEGER) >= 0 is an attempt to emulate an invocation of IS_DIGITS, perhaps showing how a user-defined operator of that name might be implemented in SQL. The character "+" is concatenated to the putatively numeric portion of the string in order to exclude values such as 'S+123' from the domain (the string '+123' can be cast as an integer but '++123' cannot).

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

Dynamic ranges- iterative control, Dynamic Ranges The PL/SQL lets you det...

Dynamic Ranges The PL/SQL lets you determine the loop range dynamically at run time, as the example below shows: SELECT COUNT(empno) INTO emp_count FROM emp; FOR i IN 1..emp_cou

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

Procedural constraint enforcement (triggers) , Procedural Constraint Enforc...

Procedural Constraint Enforcement (Triggers) SQL has an alternative method of addressing database integrity, involving event-driven procedural code. The special procedures th

Calculate days between ordering and shipping, An analyst in the quality ass...

An analyst in the quality assurance office reviews the time lapse between receiving an order and shipping an order. Any orders that have not been shipped within a day of the order

Example of except operator - sql, Example of EXCEPT Operator - SQL Ex...

Example of EXCEPT Operator - SQL Example, like its counterpart in the theory book, illustrates the convenience of allowing any table expression to be the source for an INSERT

Keyword and parameter description in pl sql, Keyword and Parameter Descript...

Keyword and Parameter Description: label_name: This is an undeclared identifier which optionally labels the PL/SQL block. When used, label_name should be enclosed by the do

Difference between 9i & 10g, Difference between 9i & 10G When Oracle r...

Difference between 9i & 10G When Oracle releases any new databases then it are having some discrepancy with them. But 10G is having much difference than oracle 9i has. Oracle

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

Using forall statement - bulk bind performance improvement, Using the FORAL...

Using the FORALL Statement The keyword FORALL instruct the PL/SQL engine to bulk-bind input collections before sending them all to the SQL engine. Though the FORALL statement

How to use the explain plan for statement, Using the student and faculty ta...

Using the student and faculty tables create a select query that outputs all students for a specific advisor. Generate the execution plan, select out the explain plan . Create an

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