Describe the architecture of a relational database, including how the Essay

Describe the architecture of a relational database, including how the data is organized. Explain a relational DBMS. What are some of the limitations of a relati - Essay Example Each column has a column name and contains values that are bound by the same type and size. For example, a column in the table S_DEPT specifies the names of the departments in the organization. A Primary key is a column or a combination of columns that is used to uniquely identify each row in a table. For example, the column containing department numbers in the S_DEPT table is created as a primary key and therefore every department number is different. A primary key must contain a value. It cannot contain a NULL value. A Foreign key is a column or set of columns that refers to a primary key in the same table or another table. You use foreign keys to establish principle connections between, or within, tables. A foreign key must either match a primary key or else be NULL. Rows are connected logically when required. The logical connections are based upon conditions that define a relationship between corresponding values, typically between a primary key and a matching foreign key. This relational method of linking provides great flexibility as it is independent of physical links between records. The entities and the relationships between them are represented as a collection of tables.   The process of deciding what the best collection of tables is for a given application is known as data-base modelling.  Ã‚   For the purpose of this document, let the definition of a good model be defined as one which enables a single change to the part of the real world being modelled to be reflected by a single change to the model. As an illustration of the sort of problem that lends itself to solution using an RDBMS consider a bank that wishes to maintain details of its branches, staff, customers and their accounts, including details of cash investment and withdrawal. Relationships are reflected by one table referencing another through the second table’s primary key.   The referencing table has a field (or fields) which correspond to the primary key field(s)