Suppose you are marketing head of 500 bedded multispecialty hospital in a metropolitan city. analyze different types of marketing environments which you will consider while preparing your marketing strategies
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The primary or natural key data can always be modified, even with databases that do not support cascading updates across related foreign keys.
Requirement changes Edit
Attributes that uniquely identify an entity might change, which might invalidate the suitability of natural keys. Consider the following example:
An employee's network user name is chosen as a natural key. Upon merging with another company, new employees must be inserted. Some of the new network user names create conflicts because their user names were generated independently (when the companies were separate).
In these cases, generally a new attribute must be added to the natural key (for example, an original_company column). With a surrogate key, only the table that defines the surrogate key must be changed. With natural keys, all tables (and possibly other, related software) that use the natural key will have to change.
Some problem domains do not clearly identify a suitable natural key. Surrogate keys avoid choosing a natural key that might be incorrect.
Requirement changes Edit
Attributes that uniquely identify an entity might change, which might invalidate the suitability of natural keys. Consider the following example:
An employee's network user name is chosen as a natural key. Upon merging with another company, new employees must be inserted. Some of the new network user names create conflicts because their user names were generated independently (when the companies were separate).
In these cases, generally a new attribute must be added to the natural key (for example, an original_company column). With a surrogate key, only the table that defines the surrogate key must be changed. With natural keys, all tables (and possibly other, related software) that use the natural key will have to change.
Some problem domains do not clearly identify a suitable natural key. Surrogate keys avoid choosing a natural key that might be incorrect.
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