Databases 0.0 / 5 ? ComputingDatabasesA2/A-levelWJEC Created by: em1lyturnerCreated on: 27-11-18 08:44 What is a flat file database? Information is held in a single table. Attribute - column. Row - record. 1 of 15 Why use a flat file database? For small amounts of data as it is simple and effective. 2 of 15 Disadvantages of a flat file... 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? a special relational database table column (or combination of columns) designated to uniquely identify all table records. 7 of 15 What are foreign keys? a column or group of columns in a relational database table that provides a link between data in two tables. 8 of 15 What are secondary keys? Made on a field that you would like to be indexed for faster searches. A table can have more than one secondary key 9 of 15 Benefits of a relational database... 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? First normal form (1NF) sets the fundamental rules for database normalization and relates to a single table within a relational database system. 13 of 15 Requirements for second normal form? The second step in normalising a database. 2NF builds on the first normal form (1NF). 14 of 15 Requirements for third normal form? The third step in normalising a database and it builds on the first and second normal forms, 1NF and 2NF. 15 of 15
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