Sql - 1

Front 1

metadata

Back 1

data about data such as table and collumn names and data types

Front 2

domain

Back 2

the entire range of value names

Front 3

delimiters

Back 3

punctuation that separates different values

Front 4

fixed-length records

Back 4

database where every entry is of the same length and thus no delimters (only maybe an offset) is needed.

Front 5

indexing

Back 5

the process for searching for and numbering/aranging delimiters so that records can be easily accessed in the future

Front 6

variable-length records

Back 6

records where each entry can have a different lenght and delimters tell you when you have reached a different entry

Front 7

entity relationship diagram

Back 7

a diagram that shows the relationships within a database.

Front 8

repitition structure

Back 8

another word for a loop

Front 9

selection statement

Back 9

command that tells sql to select certain types of data from the database

Front 10

list 11 properties of a DBMS

Back 10

look up properties of a database management system

Front 11

query

Back 11

and instruction to retrieve data from databases

Front 12

null value

Back 12

a value which has not been inserted for whatever reason

Front 13

primary key

Back 13

a collumn or collumns that contain unique and not null values. This prevents two rows from ever being equal (loss of data integrity)

Front 14

foreign key

Back 14

a collumn which values are limited to the values of the primary key which it references.

Front 15

multi-valued attributes

Back 15

collumns that require more than one entry to fill each cell

Front 16

principle of atomicity

Back 16

idea that only one value should be stored in each cell

Front 17

referential integrity

Back 17

the idea that all values in a foreign key should reference a value in another table.

Front 18

composite primary key

Back 18

same as a multi-collumn primary key

Front 19

one to many, many to one, or many to many (optional/not optional or mandatory/not mandatory)

Back 19

ways of defining how foreign keys refer to entries in the linked table

Front 20

bridge table

Back 20

a many to one table designed to connect two many to many tables and servers as an intermediate table.

Front 21

problems with redundancy

Back 21

1. requires more storage space
2. creates three types of anomolies

Front 22

update anomoly

Back 22

when updating one record you have to change the corresponding record on other rows. happens with redundant data.

Front 23

deletion anomoly

Back 23

when deleting some data causes you to loose other usefull information. happens often when data is stored only once.

Front 24

insertion anomoly

Back 24

when you can insert some data without inserting other data which may not be aplicable. Creates a problem before data is even stored.

Front 25

goals of normalization

Back 25

minimize redundancy
reduce inconsistency
avoid anomalies
reduce maintenance

Front 26

relational database

Back 26

a database that satisfies the first normal form

Front 27

first normal form

Back 27

look up requirements for first normal form

Front 28

2 types of repeating groups

Back 28

1. multiple collumns with similar information
2. mult-valued collumns

Front 29

atomic entries

Back 29

when one value is stored in each cell

Front 30

normalization rule 2

Back 30

all non-primary key items depend on all parts of the primary key

(eliminates partial dependencies)

Front 31

normalization rule 3

Back 31

all non-primary key collumns depend only on the primary key (eliminates transitive dependencies)

Front 32

5 rules for denormalization

Back 32

1. performance with realistic data is no good
2. performance can't be improved with hardware and software improvements
3. software designer understands what he is doing
4. business rules are designed to maintain the redundant data