DATABASES GLOSSARY

Sumary of Key Terms

Attribute - a column in a table.
 
Candidate key - a possible primary key.
 
Cardinality of a table - the number of records.
 
Data independence - where changing files makes no difference to the data.
 
Degree of a table - the number of attributes columns in a table.
 
Distributed database - a single logical view of several data repositories.
 
Domain - the range of acceptable values of an attribute.
 
Foreign key - an attribute that has a primary key in another table.
 
Latency - the time taken for the disc to spin round.
 
Normalisation - decomposition and division of data to check data redundancy and relevance.
 
Platter - one of the discs in a hard drive.
 
Query - a virtual table.
 
Record - a row of information which is also called a tuple.
 
Redundancy in a table - duplication of data.
 
Referential integrity - a set of rules specifying the relationship between two database tables.
 
WHERE clause - a statement to extract only those records that fulfil a specified condition.
 

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