In database design, it is a good practice to have a primary key for each table. There are two ways to specify a primary key: The first is to use part of the data as the primary key. For example, a table that includes information on employees may use Social Security Number as the primary key. This type of key is called a natural key. The second is to use a new field with artificially-generated values whose sole purpose is to be used as a primary key. This is called a surrogate key.

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Oct 06, 2014  The more columns in the primary key, the harder the database engine has to work to sort and maintain indexes, as well as process queries that reference the primary key. And with a surrogate key, you never have to worry about unexpected NULL values or the business logic changing in a way that would require modifying the schema. A surrogate key. Hi all I'm very new to the SAS World, but i have a little experience on t-sql. What i want to do is create a table or a data set with with an unique ID with an auto increment like t-sql do or a sequence like Oracle but with SAS. I've heard of a surrogate key. Can i create un surrogate key to do th. 5 Developing Services. Service-oriented development is based on the concept of services. It is the realization of business functionality via software that customers can use to compose new business applications by using existing services in the context of new or modified business processes. Aug 23, 2007  Composite Primary Keys. Thu Aug 23, 2007 by Jeff Smith in techniques, database-design. Ah primary keys such a topic! When discussing what columns to define as a primary key in your data models, two large points always tend to surface.

“There seams to be some confusion between what a Primary Key is, and what an Index is and how they are used. The Primary Key is a logical object. By that I mean that is simply defines a set of properties on one column or a set of columns to require that the columns which make up the primary key are unique and that none of them are null. In database design, it is a good practice to have a primary key for each table. There are two ways to specify a primary key: The first is to use part of the data as the primary key. For example, a table that includes information on employees may use Social Security Number as the primary key. This type of key is called a natural key.

A surrogate key has the following characteristics:

1) It is typically an integer.

A Primary Key Especially An Auto-generated Surrogate Key Is Sufficient Living

A Primary Key Especially An Auto-generated Surrogate Key Is Sufficient Life

2) It has no meaning. You will not be able to know the meaning of that row of data based on the surrogate key value.

3) It is not visible to end users. End users should not see a surrogate key in a report.

Surrogate keys can be generated in a variety of ways, and most databases offer ways to generate surrogate keys. For example, Oracle uses SEQUENCE, MySQL uses AUTO_INCREMENT, and SQL Server uses IDENTITY.

Surrogate keys are often used in data warehousing systems, as the high data volume in a data warehouse means that optimizing query speed becomes important. Using a surrogate key is advantageous because it is quicker to join on a numeric field rather than a non-numeric field. This does come at a price — when you insert data into a table, whether via an ETL process or via an “INSERT INTO” statement, the system needs to take more resources to generate the surrogate key.

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There are no hard rules on when to employ a surrogate key as opposed to using the natural key. Often the data architect would need to look at the nature of the data being modeled and stored and consider any possible performance implications. The following are examples of when it makes sense to use a surrogate key:

1) When different source systems use different keys for the same record. When we integrate the systems, instead of picking one set of keys, it is often better to use a surrogate key.

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2) When we have Type 2 Slowly Changing Dimensions. In those cases, we’ll want to use the surrogate key to ensure that we keep the history of the change.