Databases 4.5 / 5 based on 3 ratings ? ComputingDatabasesA2/A-levelOCR Created by: frankie306Created on: 05-05-16 11:32 What is a flatfile database? Information is held in a single table. Attribute - column. Row - record 1 of 15 Why use a flatfile database? For small amounts of data as it is simple and effective. 2 of 15 Disadvantages of flatfile; Large amounts of data stored can cause data redundancy 3 of 15 What is data redundancy? When data is replicated in a database 4 of 15 Disadvantages of data redundancy; In accurate data can cause legal issues e.g. Data protection act - data must be up to date 5 of 15 What are relational databases? Linked groups of small tables which use primary and foriegn keys. 6 of 15 what are primary keys uniques identifier in a table 7 of 15 What are Foreign keys? any field in a table which is the primary key in another 8 of 15 What are secondary keys? additional keys used to search for a record in a database 9 of 15 Benefits of relational databases; Remove problems formed from flatfile databases. Repetition is removed 10 of 15 What is normalisation? The process of converting a flat file database to a relational database 11 of 15 What is indexing? A data structure used to shorten the length of time it takes to search for information in a database 12 of 15 Requirements for first normal form? All attributes in a table are dependent on primary keys, each attribute contains only one piece of data. 13 of 15 Requirements for second normal form? No partial dependencies occur 14 of 15 Requirements for third normal form? No transitive dependencies (where A is dependent on B which is dependent on C therefore A is transistively dependent on C) 15 of 15
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