Unit 8

Software applications designed to manage large amounts of data are referred to as
Database Management Systems (DBMS)
• There are multiple kinds of DBMS, including:
o Key-Value Database
o Graph Database
o Document Database
o Search Database
o Relational Database
o Analytical Database
o Column-oriented Database
• Each DBMS has its benefits and shortcomings and should be chosen to match the nature
of the data stored.
• Relational databases are the most popular form of DBMS.
o Seven of the top 10 DBMS are Relational
• All databases perform at least four operation types
o Create new records
o Read existing data
o Update existing data
o Delete records in the database
• Relational DBMS have the following parts
o Table is a sequence of records, similar to a flat file or spreadsheet
o Field contains the smallest unit of meaningful information
o Record refers to a collection of data fields (one row)
o Column
• The relationship between record types can be depicted graphically with an Entity-
Relationship Diagram (ERD)
• Relationship is an association between data stored in different records
• Cardinality is the number of associations that can exist between two records
• Structured query language (SQL) is a declarative programming language for storing and
processing information in a relational database.
• A Join is a way to collect records from two tables.
• Kinds of joins include:
o INNER JOIN selects all rows from the tables as long as a join condition satisfies.
o FULL (OUTER) JOIN creates a result-set by combining the results of the left and
right joins, including all the rows.
o RIGHT JOIN returns all the rows of the rightmost table of and the matching rows
for the leftmost table.
o LEFT JOIN returns all the rows of the leftmost table of and the matching rows for
the rightmost table.

• Results from a database can be aggregated on a particular field.
• Aggregation is accomplished in SQL using the GROUP BY and an aggregation function.
• Aggregation functions include:
o COUNT(...)
o AVG(...)
o SUM(...)
o MAX(...)
o MIN(...)
o ROUND(...)
• Excel implements database-like functionality using a pivot table.
• Pivot tables aggregate records of one or more tables of a spreadsheet producing
summarized results.