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A series of questions and answers related to databases in the context of the nat 5 computing curriculum. It provides an overview of key database concepts, including the definition of a database, the advantages and disadvantages of electronic and paper-based databases, the limitations of flat-file databases, the purpose of primary and foreign keys, the types of relationships in databases, and the structure of sql queries for selecting, inserting, updating, and deleting data. The document also covers data types, validation, and the components of a data dictionary. This resource could be useful for students preparing for exams, studying database concepts, or reviewing course material related to databases and data management.
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What is a database? - A collection of related information about a set of persons or objects ( can be physical or electronic) What does DBMS stand for - database managment system Disadvantages of paper databases - - very bulky/lots of space -easy to misfile , lose or damage records -data was often duplicated -keeping records up to date was difficult and time consuming ( duplicated records may be updated in 1 but ot the other) Advatages of electronic databases - -searching, sorting and calculating operations can be done much easier -information is more easily available to users(less time to find)
Limitations of flatfile databases - -duplication of data -data may be inconsistant -insertion , deletion and update anomalies
Why is restricted choice validation used - -eliminates input errors -so users are presented wiht the only options How do dates get sorted ( ASC and DESC ) - ASC oputs earliest dates first (12/1/ before 12/2/20) DESC puts latest dates first ( 12/2/20 before 12/1/20) What is data? - Raw unprocessed facts and figures What is information? - Data that has been processedand given meaning What is a file? - Collection of structured data on a particular topic What is a record? - A collection of structured data on a particular person or thing, a row in a table What is a field? - An area on a record which contains an individual piece of data , a column
In an ER diagram the primary key is ... - underlined In an ER diagram the forgien key is ... - stared ( * ) What is a data dictionary - a description of the structure of the data held in a database What sort of information can a data dictionary include - - field name -data type -size (text fields only) -key ( P or F) -validation required -sample data What are the types of validation - -presence check -length check -range check -restricted choice
What does SQL stand for - Structured Querry Language What are the 4 types of querries - -select -insert -update -delete What is a complex sort - a sort that depends on more than 1 field What is the structure of a select querry - SELECT "the field you want to display" FROM "the table name" WHERE "the condition that needs to be met" ORDER BY "field name" ASC/DESC How do you display all fields in a select statement - SELECT * How to select fields from 2 table - SELECT tablename.fieldname