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Cyber Transit Ltd keeps up-to-date information on the processing and current position of each dispatched item. Dispatched items are the main concern of the Cyber Transit product tracking information system. Dispatched items can be characterized by item number (unique), weight, size, destination, and final date of delivery. Dispatched items are received into the Cyber Transit system at a single retail center. Retail centers are characterized by their type, unique ID and address. Dispatched items make their way to their destination via one or more Cyber Transit transportation medium (i.e. flights, truck deliveries). These transportation medium are characterized by a unique schedule number, a type (e.g. flight, truck) and a delivery route.
Create an Entity Relationship diagram that captures this information about Cyber Transit Ltd.
Convert the ER diagram in figure above into its corresponding relational schema diagram.
Saving Derived Attributes to Avoid Re-computation Data that is derived from other data should be stored in the computed form to avoid re-computation. For this, we could define
For each 1: n relationship type R involving two entities E1 and E2, we recognize the entity type (say E1) at the n-side of the relationship type R and contain primary key of the en
Using Literal Character String Example: To print IS A as one string with column name employee SELECT ENAME || ' IS A ' || JOB AS "EMPLOYEE" FROM EMP;
sql is relationally complete-justify
Give the limitations of SQL authorization. The code for checking authorization becomes intermixed with the rest of the application code. Implementing authorization by applic
The Concurrent Transactions Almost every commercial DBMS support multi-user environment. Therefore, allowing multiple transactions to proceed concurrently. The DBMS must make
What are the two main goals of parallelism? Load -balance multiple small accesses, so that the throughput of such accesses enhances. Parallelize large accesses so that the res
Define the Immediate Update The immediate update methods may apply changes to the database on disk before the transaction arrives a successful conclusion. Though, these change
Set Difference If R1 and R2 are two union compatible relations or relations then result of R3 =R1- R2 is the relation that have only those tuples that are in R1 but not in R2.
QUESTION (a)(i) Define the term database. (ii) How is it different from a database management system? (b) What is the difference between an entity and an attribute? (c
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