Database Structure Basics National Center for Immunization & Respiratory Diseases Influenza Division Pam Kennedy Analyst, McKing Consulting Regional Training Workshop on Influenza Data Management Phnom Penh, Cambodia July 27 – August 2, 2013

Course Objectives Designing a System  Function  Structure  Data Types  Data Relationships Data Entry  Data Standards  Forms Controls Control Validation  Data Security Section 1 Section 2 Questions

Designing a System Function Function of a database is to facilitate the analysis of large amounts of data quickly and efficiently Effective databases result from upfront planning before the first data table is built  Who has data /who is collecting data  What data is being collected/needs to be collected  Why is the data needed  When is data collected  Where is data collected

Designing a System Structure  How many data tables are needed?  How will data be entered?  How will data be stored?  What level of data/database security is needed?  Who needs access to the files?  Will data be used in calculations?  Will regular reports be needed?  Is there a need to export data? Database structure

Designing a System Structure Database structure  Excel is a ‘flat’ file system  A "flat file" is a plain text or mixed text which usually contains one record per lineplain textrecord  There are no structural relationships between the records.  ACCESS is a ‘relational’ system  A relational database matches data by using common characteristics found within the data set. The resulting groups of data are organized and are much easier for many people to understand.database

Designing a System Structure Excel and ACCESS both store data in a ‘column/row’ format Excel  A ‘worksheet’ is the data storage tool  Excel workbook is a collection of worksheets  Excel worksheets are ‘flat files’ ACCESS  A ‘table’ is the data storage tool (equivalent to an Excel ‘worksheet’)  Tables relate to other tables forming the basis for data analysis  Tables group like elements together  Patient information – name, address, phone, Date of Birth,  Site information - site name, site contact info, type of site

Designing a System Structure Worksheets/Tables store data within the database  Excel Worksheet  ACCESS Table Record Fields Field Value

Designing a System Data Types There are different elements of data:  Names, Dates, Cost information, Notes Data type is defined during database construction Excel and ACCESS both have default data types  Excel – ‘general’  ACCESS – ‘text’ Data type determines how data can be used in calculations  Important during analysis or data summary Commonly used data types:  Excel – general, date, currency  ACCESS – text, number, date

Designing a System Data Types Shared data types – Excel and ACCESS  Text - for use storing names, short titles, country  Number - for use storing numerical data  Date/Time - for use storing dates and can capture time  Currency - for use storing costs, price, etc. ACCESS Specific Data Types  Memo - text field without character limit – for use storing notes  In Excel – there is no character limit in any one cell  Yes/No - creates check box field in a table (yes = box checked)  AutoNumber – field that assigns an incremental number to each record

Designing a System Data Types Excel

Designing a System Data Types ACCESS

Designing a System Data Relationships ACCESS Specific What is a relational database ?  System that links data by using common characteristics  System that stores data in logical manner making analysis easier  Provide more efficient means of dealing with duplicated data An ACCESS database is composed of the following elements:  Tables – Store data  Queries – Aid in sorting, summing, calculating data  Forms – Aid data input

Designing a System Data Relationships Data relationships are critical Relationships should be set up as the database is built Questions to consider:  How do the fields in different tables relate?  Is there a common factor in all the tables? This is the unique field that will apply across all data  Consider data to be collected and how it will be used  Consider data types – relationships link data of same type

Designing a System Data Relationships Key types of relationships  One to One – A unique record in Table 1 matches an exact record in Table 2  One to Many – A unique record in Table 1 matches to several records in Table 2 SARI Data Table 1 Lab Data Table 2 Patient ID Date of specimen collection Date of VisitType of sample collected Age SexResultsPatient ID

Example of Data Relationship

Data Entry Standards Forms  Form functions  Controls Drop down Check boxes Data Validation  Queries Data Security

Data Entry Standards Why standardize?  Create common understanding  Ease comparison of data year to year  Increase efficiency for analyzing  Know where data is  Know what people are asking for  Everyone enters data in same way  Ease comparison of data from group to group  Example  Dates

Data Entry Standards Dates Football 12/2/20132/12/2013

Data Entry Standards Standards  Definition of data types during design phase ensures standardization of data  Numbers stored as numbers  Currency stored in specified currency format  Dates stored uniformly -  ‘Yes’ stored as ‘Yes’ not ‘Y’  ‘Controls’ can be used to assist in maintaining data standards  Limit data entry choices to defined terms  Excel and ACCESS have similar ‘controls’ available

Data Entry Forms Building a ‘data entry form’  Identify data fields  Determine structure  Determine data field relationship (ACCESS)  Determine data type for each data field  Dates = date type  Cost = currency  Determine common standard responses  “Yes” will by stored as ‘Yes’  Choices will be ‘Yes’, ‘No’, ‘NA’  Date format = DDMMYY or DDMMYYYY Most of these decisions should be made during database structure design

Data Entry Forms Excel

Data Entry Forms ACCESS

Data Entry Forms Queries  Allow you to view, change, and analyze data in different ways  Several types :  Select  Parameter  Crosstab  Action A select query is the most common type of query  Retrieve data from one or more tables  Group records and calculate sums, counts, averages, and other types of totals Stefano TEMPIA Microsoft Access Tutorial – Lecture 2

Data Entry Forms Select query Stefano TEMPIA Microsoft Access Tutorial – Lecture 2

Data Entry Data Security Why security  Ensure data is maintained according to set standards  Ensure access to data is controlled  Ensure accuracy of data Security levels  Excel  Workbook  Worksheet  ACCESS  Database  Record

Designing a System Database Basics Questions???

Designing a System Database Basics Final Thoughts  The database should meet your current needs and any future needs you can anticipate  Build a structure that works for you and provides what you need  Be prepared to change and adapt as your data needs change Keep it SIMPLE!

For more information please contact Centers for Disease Control and Prevention 1600 Clifton Road NE, Atlanta, GA Telephone, CDC-INFO ( )/TTY: Web: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention. THANK YOU National Center for Immunization & Respiratory Diseases Influenza Division

Designing a System Database Basics EXERCISE Setting up tables using national surveillance forms Setting up data entry controls Entering data using controls