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!
Procedural Constraint Enforcement (Triggers)
SQL has an alternative method of addressing database integrity, involving event-driven procedural code. The special procedures that can be used for this purpose are called triggers and the events that activate them are specified update operations. For example, suppose it is required for every row in IS_CALLED to have a matching row on StudentId in IS_ENROLLED_ON, enforcing a business rule to the effect that every registered student must be enrolled on at least one course. Then a triggered procedure might be activated every time INSERT is used to add a row to IS_CALLED, checking to see if a matching row exists in IS_ENROLLED_ON and raising an exception if there isn't one. But that wouldn't be sufficient to address the requirement.
Further triggers would be needed, activated by UPDATE statements on IS_CALLED and IS_ENROLLED_ON that cause changes to StudentId values in either of those tables, and by DELETE statements on IS_ENROLLED_ON. As this simple example demonstrates, use of triggered procedures for constraint enforcement can be complicated and error-prone. As one practitioner told me, "It quickly gets so complicated that it's almost impossible for a human not to make errors..., and even when you're not facing a 'complicated' case, the work to be done is tedious and boring".
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
Cursor Variables: To execute the multi-row query, the Oracle opens an unnamed work region that stores the processing information. You can use an explicit cursor that names
I need to write one function and one procedure to query a Oracle 10.1 DB using PL SQL. I have the schema and exact queries...along with work Ive started and a template to put the a
I would like to have a custom MS Access database designed and coded that would help me schedule my customer's orders and that would help me track my employees production output and
Using a Join on 2 tables, select all columns and all rows from the tables without the use of a Cartesian product. Query: SELECT * FROM EMPLOYEE1 JOIN CONTRACT ON EMPLOYEE
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
Updating Variables For assignment, SQL uses the key word SET, as in SET X = X + 1 (read as "set X equal to X+1") rather than X: = X + 1 as found in many computer languages.
I want to implement heap sort algorithm in pl sql please share the source code for guidance
BETWEEN and NOT BETWEEN Operator in SQL Example: Restricting exam marks to between 0 and 100 CREATE ASSERTION Marks_between_0_and_100 CHECK (NOT EXISTS (SELECT * FROM
How Transactions Guard Your Database The transaction is a sequence of SQL data manipulation statements which does a logical unit of work. The Oracle treats the sequence of SQL
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