admfuck - 1. Top-down design starts by identifying the data...

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1. Top-down design starts by identifying the data sets, then defines the data elements for each of those sets. The entities are defined before the attributes per entity. 2. Bottom-up design first identifies the data elements (items), then groups them together in data sets. The attributes are defined first then are grouped to form the entities. . 3. Centralized design is more productive when the data component is composed of a relatively small number of objects and procedures. The database design can be represented in a fairly simple database. A single conceptual design is completed and then validated. 4. Decentralized design is more appropriate for systems with data components that have a considerable number of entities and complex relations on which complex operations are performed. It is also applied when the problem itself is spread across several operational sites and each element is a subset of the entire data set. 5. design philosophy is essentially based on the company’s structure as well as the scope and size of the system. 6. A transaction is a logical unit of work that must be entirely completed or entirely aborted. 7. a transaction is any action that reads from and/or writes to a database. It may be as simple as a SELECT statement; it may consist of any combination of SELECTs, INSERTs, UPDATEs and/or DELETEs. 8. A consistent database state is one in which all data integrity constraints are satisfied. 9. A database request is the equivalent of a single SQL statement in an application program or transaction. 10. Atomicity – this requires that all operations of a transaction be completed; if not, the transaction is aborted. 11. Consistency – indicates the permanence of the database’s consistent state. 12. Isolation – means that the data used during the execution of a transaction cannot be used by a second transaction until the first one is completed. This is particularly useful in a multi-user database environment.
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13. Durability – ensures that once transaction changes are done (committed), they cannot be undone or lost, even in the vent of system failure. 14. Serializability – ensures that the concurrent execution of several transactions yield consistent results. That is, the concurrent execution of transactions T1, T2, and T3 yields results that appear to have been executed in serial order. 15. ANSI has defined standards to govern over SQL database transactions. 16. A COMMIT statement is reached. Changes are permanently recorded within the database. 17.
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admfuck - 1. Top-down design starts by identifying the data...

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