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!
WHEN or THEN Key Constraints
Suppose a table has two columns representing a period of time throughout which the information conveyed by the other columns is recorded as having been the case. A salary history table for employees, with columns From and To for dates defining the applicable time periods, would be a good example.
A constraint is needed to avoid the possibility of an employee being shown as having two different salaries on the same day, which could happen if two rows for the same employee have overlapping periods indicated by their From and To dates. The term "WHEN/THEN constraint" appeals to the notion of "unpacking" the table so that each row is replaced by one or more rows, one for each date contained in its from-to period: when the relation is unpacked, then the given key constraint (e.g., on employee number and date) is to hold.
Write a program to implement the inverted file shown in the slides (Simple Index file, LabelID file and Data file). Use the Avail_List to point at the deleted Label IDs so that th
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
Defining Autonomous Transactions To define an autonomous transaction, you use the pragma (compiler directive) AUTONOMOUS_TRANSACTION. The pragma instructs the PL/SQL compiler
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
Explicit Cursors The set of rows returned by the query can include zero, one, or multiple rows, depending on how many rows meet your search criteria. Whenever a query returns
Using Operator VALUE: As you may expect, the operator VALUE returns the value of an object. The VALUE takes its argument a correlation variable. For illustration, to return a
Project Description: I want a database for large governmental and private data sets on one country that will be easily extended to other countries in the future. Also, the datab
Using a Host Variable You can declare the cursor variable in the PL/SQL host environment like an OCI or Pro C program. To use the cursor variable, you should pass it as a host
How do I display usernames for students from a student table, assigning each student a username initials001 (initials is the actual student initials), and if the students initials
Relational Operators The relational operators permit you to compare randomly complex expressions. The list below provides the meaning of each operator:
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