CSS/559 Data Base Concepts II
Data Dictionary and Normalization Guidelines
The purpose of a data dictionary is to define the objects and data within an organization's database management system. This metadata does not contain any of the database's data, but only information about the structure, storage and use of the database's data. A data dictionary can be stored in files or documents, or can be stored within a database in the DBMS. For example, a database may contain an employee table that has an emp_no column and an identification_no column. A data dictionary can explain that the emp_no column is an integer value containing the employee number assigned by the system. When a new employee is added to the system, a next number value is retrieved from a next number table and assigned to the new employee record. The data dictionary would also explain that the identification_no column is an alpha-numeric value that contains the employee's social security number for US residents and for non-US residents contains the employee's country code followed by their work visa number. The data dictionary can also be used to define aliases for the column names since column names can become a bit cryptic. It can also provide information regarding different type of database objects such as tables, views, stored procedure, user groups, functions, triggers, etc. Furthermore, it can also provide information on how database objects are related to one another. An important aspect of a data dictionary is that it provides database administrators, programmers, and any other user of the database data a clear, consistent and centralized source of information about the database objects and the data stored within or accessed by them. This helps to ensure that the data is used appropriately and can reduce data redundancy. A data dictionary is also important when you are integrating your data with another system, since you will be certain of which data needs to be integrated. Using a...
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