mis 431 Flashcards
data
building blocks of information
information
reveals meaning of data
database’s house:
- end user data
- metadata
database models
collection of logical constructs used to represent data structure & relationships within the database
In
checks for the value in a set
between
in the range
BETWEEN
defines limits
IS NULL
checks for nulls
LIKE
checks for similar string
IN
checks for value in a set
EXISTS
opposite of ‘IS NULL’
information
reveals meaning of data
database’s house:
- end user data
- metadata
Database Management Systems
- Manage database structure
- controls access to data
- contains query language
poor database design
results in unwanted data redundancy
rollback command
restores database back to previous condition if COMMIT hasn’t been used
order by
groups the data as a single summary row
(be at the end of the query)
Having clause
provides a condition that is applied to each group of entities (as created by the GROUP BY), & only the groups that satisfy the condition are kept (after GROUP BY)
self join
compares different data in same query. Must rename tables
union
is the output of multiple queries
VIEW
relation that you define based on the underlying relations available to you in your database schema
DISTINCT
must not be specified
end user data
- data provided by a data warehouse
- data created by end users for query processing
metadata
data that describes and summarizes basic info about other data
