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Databases.

Databases. Revision tip: Focus on the things you find difficult first. “Every lesson counts – don’t waste a minute.”. Importance of databases. Give a definition of a database. (2 marks) ……………………………………………………............................................

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Databases.

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  1. Databases. Revision tip: Focus on the things you find difficult first.

  2. “Every lesson counts – don’t waste a minute.”

  3. Importance of databases. • Give a definition of a database. • (2 marks) • ……………………………………………………............................................ • .................................................................................................................... • ……………………………………………………............................................ • ...................................................................................................................... • ……………………………………………………............................................ • ...................................................................................................................... • ……………………………………………………............................................ • ...................................................................................................................... • ……………………………………………………............................................ • ...................................................................................................................... • Most organisations depend on their databases in order to operate. Because of this databases need to be:(4 marks) • i) ……………………………………………………............................................ • ........................................................................................................................ • ii) ……………………………………………………............................................ • ........................................................................................................................ • iii) ……………………………………………………............................................ • ........................................................................................................................ • iv) ……………………………………………………............................................ • ........................................................................................................................

  4. Exam tip:Remember that validation can be set up in any way that the database designer wants. Data security & data integrity Explain the term ‘verification’. (2 marks) ……………………………………………………............................................ .................................................................................................................... ……………………………………………………............................................ ...................................................................................................................... ……………………………………………………............................................ ……………………………………………………............................................ ...................................................................................................................... What is a ‘check digit’. (2 marks) ……………………………………………………............................................ .................................................................................................................... ……………………………………………………............................................ ...................................................................................................................... ……………………………………………………............................................ ..................................................................................................................... ……………………………………………………............................................ Explain the term ‘validation’. (3 marks) ……………………………………………………............................................ .................................................................................................................... ……………………………………………………............................................ ...................................................................................................................... ……………………………………………………............................................ ...................................................................................................................... ……………………………………………………............................................ ...................................................................................................................... ……………………………………………………............................................ ...................................................................................................................... A data table is set up to hold personal details of customers for an online business. Describe how the following fields would be validated: (8 marks) (a) Surname ……………………………………………………............................................ .................................................................................................................... (b) Date of birth ……………………………………………………............................................ .................................................................................................................... (c) Gender ……………………………………………………............................................ .................................................................................................................... (d) Credit limit ……………………………………………………............................................ .................................................................................................................... What is meant by a range check? (2 marks) ……………………………………………………............................................ .................................................................................................................... ……………………………………………………............................................ ...................................................................................................................... ……………………………………………………............................................ ...................................................................................................................... ……………………………………………………............................................

  5. Data redundancy Flat file vs. Relational What is a flat file database? (1 mark) ……………………………………………………............................................ .................................................................................................................... ……………………………………………………............................................ ...................................................................................................................... 6. Here is part of a database of customer details: Explain what a relational database is. (3 marks) ……………………………………………………............................................ .................................................................................................................... ……………………………………………………............................................ ...................................................................................................................... ……………………………………………………............................................ ..................................................................................................................... ……………………………………………………............................................ ..................................................................................................................... ……………………………………………………............................................ (a) Define the term data redundancy.(1 mark) ……………………………………………………............................................ .................................................................................................................... ……………………………………………………............................................ (b) Explain how data redundancy affects this table.(2 marks) ……………………………………………………............................................ .................................................................................................................... ……………………………………………………............................................ ...................................................................................................................... Explain what problems might occur as a result of the redundancy in this example.(2 marks) ……………………………………………………............................................ .................................................................................................................... ……………………………………………………............................................ ...................................................................................................................... (d) Explain how the data could be stored to eliminate this problem.(2 marks) ……………………………………………………............................................ .................................................................................................................... ……………………………………………………............................................ ......................................................................................................................

  6. Database Management System (DBMS) • Describe four features of a typical DBMS. • (4 marks) • i) ……………………………………………………............................................ • ........................................................................................................................ • ii) ……………………………………………………............................................ • ........................................................................................................................ • iii) ……………………………………………………............................................ • ........................................................................................................................ • iv) ……………………………………………………............................................ • ........................................................................................................................ Give the data that would result from running the following queries on the table below: (8 marks) (a) SELECT Surname, City WHERE Sex = “m” ……………………………………………………............................................ .................................................................................................................... (b) SELECT Surname, City WHERE Sex = “m” AND Years in employment > 3 ……………………………………………………............................................ .................................................................................................................... (c) SELECT Surname, Salary WHERE Years in employment < 4 AND Salary > 35000 ……………………………………………………............................................ .................................................................................................................... (d) SELECT Surname WHERE City = “Birmingham” OR Years in employment = 4 ……………………………………………………............................................ .................................................................................................................... Construct a query that would produce the following result: (a) A list of surnames and salaries of all female employees who live in Birmingham. (2 marks) ……………………………………………………............................................ .................................................................................................................... ……………………………………………………............................................ Explain the difference between an entity and a table. (2 marks) ……………………………………………………............................................ ..................................................................................................................... ……………………………………………………............................................ ..................................................................................................................... ……………………………………………………............................................ ……………………………………………………............................................ ……………………………………………………............................................ ……………………………………………………............................................ Describe two ways in which a query can be constructed. (2 marks) ……………………………………………………............................................ ..................................................................................................................... ……………………………………………………............................................ ..................................................................................................................... ……………………………………………………............................................ ……………………………………………………............................................ ……………………………………………………............................................ ……………………………………………………............................................

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