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!
Assigning and Comparing CollectionsOne collection can be assigned to other by an SELECT, INSERT, UPDATE, or FETCH statement, an assignment statement, or by a subprogram call. As the illustration shown below, the collections should have the same datatype. Having the similar element type is not enough.DECLARETYPE Clientele IS VARRAY(100) OF Customer;TYPE Vips IS VARRAY(100) OF Customer;group1 Clientele := Clientele(...);group2 Clientele := Clientele(...);group3 Vips := Vips(...);BEGINgroup2 := group1;group3 := group2; -- illegal; Various datatypes becomes automatically null (and should be reinitialized). Now consider the illustration as shown below: DECLARETYPE Clientele IS TABLE OF Customer;group1 Clientele := Clientele(...); -- initializedgroup2 Clientele; -- atomically nullBEGINIF group1 IS NULL THEN ... -- condition yields FALSEgroup1 := group2;IF group1 IS NULL THEN ... -- condition yields TRUE...END;Similarly, if you assign the non-value NULL to a collection, the collection becomes automatically null.Assigning Collection ElementsYou can assign the value of an expression to the specific element in a collection by using the syntaxcollection_name(subscript) := expression;Where the expression yields a value of the type specified for elements in the collection type definition. If the subscript is null or not convertible to an integer, the PL/SQL raises the predefined exception VALUE_ERROR. If the collection is automatically null, then the PL/SQL raises COLLECTION_IS_NULL. Some of the examples are shown below:DECLARETYPE NumList IS TABLE OF INTEGER;nums NumList := NumList(10,20,30);ints NumList;...BEGIN...nums(1) := TRUNC(high/low);nums(3) := nums(1);nums(2) := ASCII(’B’);/* Assume execution continues despite the raised exception. */nums(’A’) := 40; -- raises VALUE_ERRORints(1) := 15; -- raises COLLECTION_IS_NULLEND;Comparing Whole CollectionsThe Nested tables and varrays can be automatically null; therefore they can be tested for the nullity, as the example below shows:DECLARETYPE Staff IS TABLE OF Employee;members Staff;BEGIN...IF members IS NULL THEN ... -- condition yields TRUE;END;Though, the collections cannot be compared for equality or inequality. For illustration, the IF condition below is illegal as shown:DECLARETYPE Clientele IS TABLE OF Customer;group1 Clientele := Clientele(...);group2 Clientele := Clientele(...);BEGIN...IF group1 = group2 THEN -- causes compilation error...END IF;END;This restriction also applies to implicit the comparisons. For illustration, the collections cannot appear in an ORDER BY, GROUP BY, or DISTINCT list.
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
Use Object Types and Collections The Collection types and object types increase your efficiency by allowing for the realistic data modeling. The Complex real-world entities an
%FOUND Until the SQL data manipulation statement is executed, the %FOUND yields NULL. Afterward, the %FOUND yields TRUE, when an INSERT, UPDATE, or DELETE statement affected o
Architecture The PL/SQL run-time system and compilation is a technology, not an independent product. Consider this technology as an engine that compiles and executes the PL/SQL
Raise_application_error - procedure of package DBMS_STANDARD , allows to issue an user_defined error messages by stored sub-program or database trigger.
Parameter and Keyword Description: table_reference: This keyword identifies the table or view that should be accessible when you execute the UPDATE statement, and for wh
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
Special cases of projection This section describes the identity projection, r {ALL BUT}, and the projection on no attributes, r { }, which yields TABLE_DUM when r is empty, ot
Updating by insertion Syntax : INSERT INTO ENROLMENT VALUES (SID ('S4'), 'Devinder', CID ('C1'));
DELETE Statement The DELETE statement eliminates whole rows of data from the specified table or view. Syntax:
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