Surrogate Key is the solution for critical column problems.
For example the customur purcshases different items in differnt locations for this situation we have to maintain historical data.
By using surrogate key we can introduce the row in the datawarehouse to maintain historical data.
surrogate key - A unique primary key generated by the RDBMS that is not derived from any data in the database and whose only significance is to act as the primary key.
A surrogate key is frequently a sequential number (e.g. a Sybase "identity column") but doesn't have to be. Having the key independent of all other columns insulates the database relationships from changes in data values or database design and guarantees uniqueness.
Some database designers use surrogate keys religiously regardless of the suitability of other candidate keys. However, if a good key already exists, the addition of a surrogate key will merely slow down access, particularly if it is indexed.
A surrogate key is frequently a sequential number (e.g. a Sybase "identity column") but doesn't have to be. Having the key independent of all other columns insulates the database relationships from changes in data values or database design and guarantees uniqueness.
Some database designers use surrogate keys religiously regardless of the suitability of other candidate keys. However, if a good key already exists, the addition of a surrogate key will merely slow down access, particularly if it is indexed.
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