Database Systems Test 1 Review

CS 4210 Chapters 1-4

anomalies

problems that occur in poorly planned databases

insertion anomaly

when you add an entry to a table but your missing info for one or more of the columns

deletion anomaly

when you delete an entry in a table and it takes some info that you needed

update anomaly

when you update an entry in the table and it caused other information to be out of date

1NF requirements

Has to be a relation and have a primary key

2NF requirements

Is in 1NF and all non key columns are dependent on the primary key (it can be used to uniquely identify stuff) . Also has a single column primary key

3NF Requirements

Is in 2NF and there are no dependencies between two non-key columns

BCNF Requirements

Is in 3NF and there are all determinants are candidate keys

4NF Requirements

is in BCNF and has no multivalued dependencies

what is a normalized database

A relational database with reduced redundancies

primary key

key used to unique identify entries. specific choice of minimal attributes to identify entry.

foreign key

a column in a table that is a primary key of another table

composite key

a key with multiple columns (i think)

Microsoft Access

personal database system. combination of relational Microsoft jet database engine and a GUI . Intended for individuals and small groups.

functional dependencies

tells us how columns are related. If each entry has a unique value for another one, then column A determines column B . A→B

Read-only databases

non-operational databases using data extracted from operational ones. used in Data warehouses and BI systems. Used for querying, reporting , and data mining.

DBMS

Database Management System. computer program used to create, process, and administer a database