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Define Timestamp ordering
Ans In timestamp-based method, a serial order is made among the concurrent transaction by assigning to every transaction a unique nondecreasing number. The common value assigned to each transaction is the system clock value at the beginning of the transaction, therefore the name timestamp ordering. This value then can be employed in deciding the order in which the conflict between two transactions is resolved. A transaction along with a smaller timestamp value is considered to be an "older" transaction as compared to another transaction with a larger timestamp value.
Foreign Keys and NULL Let us take the relation: DEPT DEPT ID DNAME BUDGET D1 M
Define NULL value NULL value NULL means something is unknown. It does NOT mean null (the digit 0). Null is as well employed as attribute value for a particular entity in which
In case of entity integrity, the primary key may be declared? In a case of entity integrity primary key may be not Null.
Define page. The database is partitioned into some number of fixed-length blocks, which are referred to as pages.
List any two disadvantages of a database system ? The disadvantages of database system are: • Database systems are difficult, complex, and time-consuming to design. • Substanti
DROP TABLE Command: When an existing object is not needed for further use, it is always better to eliminate it from the database. To remove the existing object from the databas
what is natural join?
Write short notes on domain relational calculus The domain relational calculus uses domain variables that take on values from an attribute domain rather than values for whole t
External failure : A failure can also result because of an external cause, such as earthquakes, fire, floods, etc. The database must be duly backed up to avoid troubles occurring d
What is view in SQL? How is it defined? Any relation that is not part of the logical model, but is made visible to a user as a virtual relation is known as a view. We descri
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