Why relationships are important in a databaseThe relationship is a critical factor and component of a database. A relationship establishes the link between the pair of tables, which are logically connected to one another. Each pair of tables is logically interrelated through the data contained in each of the tables. Second, a relationship is important since it helps to refine further the structure of the table and reduce the redundant data. As one establishes the relationships between a pair of tables, he will inevitably make few modifications to that particular table structure. Third, a relationship helps to draw data from multiple tables at the same time (Schmidt & Brodie, 2012).

The purpose of a query in relational database
A query has a specific function in a database, for instance, a database query is structured and designed to retrieve a specific result from the database. The query is often formulated by the user following a particular predefined format. After a thorough search through the set of data, the information pertinent to that particular query is filtered from the pool of data and reported to the user (Obe & Hsu, 2011).

The important concepts related to database design
It is a common idea for people who are new to the relational database to relate the design of a database like they would do to the Excel-like spreadsheet. The tables used in the relational database are aligned to form a web or sort where the data required for a query are spread over some tables (Hernandez, 2013). Therefore, the imperative concept in the design of a database is that each table in the database must be properly designed to cater for the data each table will store and the other tables in the web. The other important aspect important in the design of the database is Normalization. Normalization pertains to the design of the database table using a set of guidelines that must be followed strictly (Paredaens, De Bra, Gyssens & Van Gutch, 2012). The steps used in Normalization are referred to as “The Normal Forms (NF).”

References
• Hernandez, M. J. (2013). Database design for mere mortals: A hands-on guide to relational database design. New Jersey, NJ: Pearson Education.
• Obe, R., & Hsu, L. (2011). PostGIS in action. Manning Publications Co.
• Paredaens, J., De Bra, P., Gyssens, M., & Van Gutch, D. (2012). The Structure of the Relational Database model (Vol. 17). Springer Science and Business School.
• Schmidt, J. W., & Brodie, M. L. (Eds). (2012). Relational database systems: Analysis and Comparison. Springer Science and Business School.