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The database files accept the actual data and are typically the biggest in size. Depending on their shape, the tables for all the user operation can go in one database file-but that's not an unique situation because it does not create the database structure very flexible for controlling access to storage for different accounts, putting the database on different storage disk drives, or backing up and restoring just phase of the database. You must have at least one database file but generally, more than one file are needed. In terms of accepting and using the data in the other objects and tables, the number of the folders is immaterial. The database files are not variable in size and never goes bigger than the size at which they were prepared
A View may be defined of as a virtual table, that is, a table that does not really exist in its own right but is instead inferred from one or more underlying base data table. T
Example: RELATIONAL SCHEMA for PERSON: PERSON (PERSON_ID: integer, NAME: string, AGE: integer, ADDRESS: String) RELATION INSTANCE In this instance, m = 3 and n = 4
Order by clause By using this rows can be sorted It is used in the last portion of select statement By default it gets ascending order DESC: is used
Define canonical cover? A canonical cover Fc for F is a set of dependencies like F logically implies all dependencies in FC and Fc logically shows all dependencies in F.
Association as a cache This association must be updated when any new element is added to it, but testing for overlap using association is more efficient. Figure:
Explain the concept of a data model ? Data Model - Model is an abstraction procedure which hides irrelevant details although highlighting details relevant to the application
In tuple relational calculus P1 → P2 is equivalent to ? A In tuple relational calculus P1→ P2 is equivalent to ¬P1 V P2. (The logical implication expression A B, meaning
Ways for Selecting Data Structure Algorithms operate on data structure. Therefore, selection of the best algorithm means selecting the best data structure from whole bunch. Th
Question: In a multi-user database environment, locking mechanisms can be used to solve the three basic problems of concurrency. On the other hand, however, locking may also le
Explain Strict Two-Phase locking A transaction T does not release any type of its exclusive (X) locks until that transaction commits or aborts. In this method no other transact
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