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What is the difference between Data Ware Housing and Data Mining?
What is a triggers ?What are its uses?8,660 Views |
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Data Warehousing is the technologies and STORAGE OF DATA so that the data is organized is such a way that it can be easily analyzed, extracted, synthesized, and otherwise understood by the end user.
Data Mining is the actual QUERYING OF THE DATA in a Data Warehouse to understand the data by identifying patterns in the relationships between the data objects.
dataware housing is responsible for keeping data while data mining is searching for a certain data
keeping the data in organized and user friendly way is data ware housing where as searching is data mining.
In a DBMS, a trigger is a SQL procedure that initiates an action (i.e., fires an action) when an event (INSERT, DELETE or UPDATE) occurs. Since triggers are event-driven specialized procedures, they are stored in and managed by the DBMS. A trigger cannot be called or executed; the DBMS automatically fires the trigger as a result of a data modification to the associated table. Triggers are used to maintain the referential integrity of data by changing the data in a systematic fashion.
Triggers are stored procedures which are invoked automatically by the database server in response to DML statemants like insert, update and delete on the associated table. They are used to specify integrity constraints.
Triggers can be areore triggers or after triggers.
Row triggers : executed once for every record that is affected by DML statement.
Statement trigger : executed only once(for a particular record) irrespective of the number of records that are affected.
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