Lab #8 Database Management & Queries

Stefanie Wieschalla

Geog 206

Part 1:

1. The primary functions of a database management system is organizing and manipulating data. This includes data independence, which makes it possible to make changes in the database structure in ways that are evident to any use or program. Furthermore, it provides for multiple user views and hence DBMs can reformat data without human intervention to meet exact input requirements of different users. Lastly, these systems also allow centralized control and maintenance of important data. 

2. In a one-to-one relationship, a row in table A can have no more than one matching row in table B, and vice versa. A one-to-one relationship is created if both of the related columns are primary keys or have unique constraints. However, this type of relationship is not common because most information related in this way would be all in one table. A one-to-many relationship is the most common type of relationship. In this type of relationship, a row in table A can have many matching rows in table B, but a row in table B can have only one matching row in table A. For example, the Publishers and Titles tables have a one-to-many relationship: each publisher produces many titles, but each title comes from only one publisher. A one-to-many relationship is created if only one of the related columns is a primary key or has a unique constraint.

3. Relational databases are so popular because they are more flexible than most other design models. The organization is very straightforward and thus east to learn, understand and implement when compared to other database designs. Besides that, table structure does not restrict processing or queries. It can lodge a wide range of data types and therefore it is not necessary to know in advance the kind of queries, sorting, and searching that will be performed on the database.

Part 2:

4.

a. The Data Type of the LAN_USE field in the Landuse feature class is text since it is left justified and makes use of special characters as for instance dashes and spaces.

b. The Data Type of the LAN_USE field in the LanduseInfo.dbf table is also text.

5.

a. The new fields that have been joined are all the columns that were in the stay alone tables, which are: the general column, the description column, the type column, a square miles column, an acres column, a shape length column, and finally a shape area column.

e. There exists 92236.771795 total acres of open lands in this new feature class. 

f.

g.