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  • Here are some recommended maximum lengths:First names and last names-> 25 characters handles a first name, while 50 characters each plays it safe for a long, hyphenated last name->Middle initial-> One character->(Sometimes common sense is right->)Email address-> Go with 50 characters-> Email addresses closer to 100 characters have turned up in the wild (Google "world's longest email address" for more), but they're unlikely to reach your database->Cities, states, countries, and other places-> Although a Maori name for a hill in New Zealand tops out at over 80 characters (see http://en->wikipedia->org/wiki/Longest_word_in_English), 50 is enough for most practical purposes->Street address-> A street address consists of a number, followed by a space, then the street name, another space, and the street abbreviation (like Rd or St)-> Fifty characters handles it, as long as you put postal codes, cities, and other postal details in other fields->Phone numbers, postal codes, credit card numbers, and other fixed-length text-> Count the number characters and ignore the placeholders, and set the maximum to match-> If you want to store the phone number (123) 456- 7890, make the field 10 characters long-> You can then store the phone number as 1234567890, but use an input mask (Section 4->2) to add the parentheses, spaces, and dash when you display it-> This approach is better because it avoids the headaches that result from entering similar phone numbers in different ways->Description or comments-> 255 characters fits three or four average sentences of information-> If you need more, consider the memo data type instead (Section 2->3->2)->
  • As with a text field, when you create a number field, you need to set the Field Size property to make sure Access reserves the right amount of space->
  • AutoNumber values have one minor problem: they give a clue about the number of records in a table->Random AutoNumber value-> To use, change the New Values field property from Increment to Random-> Now you'll get long numbers for each record, like 212125691, 1671255778, and -1388883525-> You might use random AutoNumber to create values that other people can't guess-> (For example, if you have an Orders table that uses random values for the OrderID field, you can use those values as confirmation numbers->) However, random AutoNumbers are rarely used in the Access world->Replication IDs-> Replication IDs are long, obscure codes like 38A94E7B-2F95-4E7D-8AF1-DB5B35F9700C that are statistically guaranteed to be unique-> To use them, change the Field Size property from Long Integer to Replication ID-> Replication IDs are really used only in one scenarioif you have separate copies of a database and you need to merge the data together in the future-> The next section explains that scenario->

Information Systems Information Systems Presentation Transcript

  • <li>Information Management and Control<br /></li><li>Information Concepts<br />Data vs-&gt; Information<br />Data – raw facts <br />Information – a collection of facts in such a way that they have additional value of the facts themselves; Processed data-&gt;<br /></li><li>The Characteristics of a valuable Information<br />Accurate – Accurate information should be error free-&gt; In some cases, inaccurate information is generated because inaccurate data is fed into the transformation process (this is commonly known as garbage in, garbage out [GIGO])-&gt;<br /></li><li>The Characteristics of a valuable Information<br />Complete – Complete information contains all important facts-&gt;<br />Economical – Information should be relatively economical to produce-&gt; Decision makers always balance the value of information with the cost of producing it-&gt;<br />Flexible – Flexible information can be used for a variety of purposes-&gt;<br /></li><li>The Characteristics of a valuable Information<br />Reliable – Reliable information can be depended on-&gt; In many cases, the reliability of information depends on the reliability of the data collection method-&gt;<br />Relevant – Relevant information is important to the decision maker-&gt;<br /></li><li>The Characteristics of a valuable Information<br />Simple – information should be simple, not overly complex-&gt; Sophisticated and detailed information may not be needed-&gt; In fact, too much information can cause information overload, wherein the decision maker has too much information and is unable to determine what is really important-&gt;<br /></li><li>The Characteristics of a valuable Information<br />Timely – timely information is delivered when it is needed-&gt;<br />Verifiable – information should be verifiable-&gt; This means that you can check it to make sure that it is correct, perhaps by checking many sources for the same information-&gt;<br /></li><li>The Characteristics of a valuable Information<br />Accessible – information should be accessible by authorized users and provided in the right format and at the right time to meet their needs-&gt;<br />Secure – Information should be secure from access by unauthorized users-&gt;<br /></li><li>What is Information Technology?<br />Information technology refers to all forms of technology applied to processing, storing, and transmitting information in electronic form-&gt; The physical equipment used for this purpose includes computers, communications equipment and networks, fax machines, and even electronic pocket organizers-&gt;<br /></li><li>What is an information system (IS)?<br />An information system (IS) is a set of interrelated components that collect (input), manipulate (process), and disseminate (output) data and information and provide a feedback mechanism to meet an objective-&gt;<br /></li><li>Input, Processing, Output and Feedback<br />Input – the activity of gathering and capturing raw data-&gt;<br />Processing – converting or transforming data into useful output-&gt;<br />Output – production of useful information usually in the form of documents and reports-&gt;<br />Feedback – output that is used to make changes to input or processing activities-&gt;<br /></li><li>Manual and Computerized Information Systems<br />A Manual Information System gathers (input), manipulates (processing), and disseminates (output) data and information using the conventional means possible having very little if not the absence of computerization-&gt;<br /></li><li>Manual and Computerized Information Systems<br />A Computer Based Information System (CBIS) is a single set of hardware, software, databases, telecommunications, people and procedures that are configured to collect, manipulate, store, and process data into information-&gt;<br /></li><li>Technology Infrastructure<br />All the hardware, software, databases, telecommunications, people, and procedures that are configured to collect, manipulate, store, and process data into information-&gt;<br /></li><li>Hardware<br />Computer equipment used to perform input, processing and output activities-&gt;<br />Input devices includes keyboards, automatic scanning devices, equipment that can read magnetic ink characters, etc-&gt; <br />Processing include the Central Processing Unit and main memory-&gt;<br />Output devices include computer screens, printer, and even secondary storage devices-&gt;<br /></li><li>Software<br />The computer programs that govern the operation of the computer-&gt;<br />These programs allows the computer to perform processes such as payroll, accounting, etc-&gt;<br /></li><li>Databases<br />An organized collection of facts and information-&gt;<br />An organization’s database contains facts and information about customers, products, employees, and those entities which has significance to the organization-&gt;<br /></li><li>Telecommunications<br />The electronic transmission of signals for communications-&gt;<br />This enables the organizations to carry out their processes and tasks through effective computer networks-&gt;<br /></li><li>Telecommunication Media<br />Networks – connected computers and computer equipment in a building, around the country and around the world to enable electronic communication-&gt;<br />Internet – the world’s largest computer network, actually consisting of thousands of interconnected networks, all freely exchanging information-&gt;<br /></li><li>People<br />People are the most important element in most computer-based information system-&gt;<br />Information systems personnel include all the people who manage, run, program, and maintain the system-&gt;<br />Users are any people who use information systems to get results-&gt; This includes financial executives, manufacturing operators, and other computer users-&gt;<br /></li><li>Procedures<br />The strategies, policies, methods and rules for using a Computer Based Information System (CBIS)-&gt;<br /></li><li>E-Commerce<br />Any business transaction executed electronically between parties such as: <br />Companies (business-to-business)<br />Companies and consumers (business-to-consumer)<br />Business and the public sector; and<br />Consumers and the public sector<br /></li><li>Take home activity<br />Search through several business magazines (Business Week, Computer World, PC Week, etc-&gt;) or Newspapers, and look for recent articles that discusses the use of information technology to deliver significant business benefits to an organization-&gt; Use the internet to gather more information about the same organization discussed in the article-&gt; <br />Prepare a one-page summary of the different resources you tried and their ease of use and effectiveness-&gt; <br />Write the name of the article and its source, then the different sites where you got more information about the organization-&gt;<br /></li><li>Format:<br />Article Name – Source<br />Web resources:<br />Source 1<br />Source 2<br />Source 3<br /> This is a sample summary of the ease of using the different resources-&gt;<br /></li><li>Working with Databases <br />Microsoft Access 2007<br />(11/23/09 Lab discussion)<br /></li><li>Databases and DBMS<br />A database is a collection of interrelated data items that are managed as a single unit-&gt;<br />DBMS (Database Management Systems) is a software provided by software vendors(e-&gt;g-&gt; Microsoft Access, Oracle, Microsoft SQL Server, Sybase, DB2, INGRES, and MySQL)-&gt;<br /></li><li>Tables<br />The primary unit of storage in the relational model is the table, which is a two-dimensional structure composed of rows and columns-&gt; Each row represents one occurrence of the entity that the table represents, and each column represents one attribute for that entity-&gt;<br /></li><li>How to create a database?<br />Open Microsoft Office Access 2007-&gt;<br />Select Blank Database<br />At the lower right corner of the window, select the location and filename of the database then click on the Create button-&gt; <br /></li><li>Customizing Tables<br />Design view lets you precisely define all aspects of a table before you start using it-&gt; <br />Datasheet view is where you enter data into a table-&gt; Datasheet view also lets you build a table on the fly as you insert new information-&gt; <br /></li><li>Access Data Types<br /></li><li>Text<br />Numbers, letters, punctuation, and symbols, up to a maximum of 255 characters (an average-sized paragraph)-&gt;<br />Examples:<br /> Names, addresses, phone numbers, and product descriptions-&gt; This data type&amp;apos;s the most common-&gt;<br /></li><li>Memo<br />Large amounts of unformatted text, up to 65,536 characters (an average-sized chapter in a novel)-&gt;<br />Examples:<br />Articles, memos, letters, arrest warrants, and other short documents-&gt;<br /></li><li>Number<br />A variety of different kinds of numbers, including negative numbers and those that have decimal places-&gt;<br />Examples:<br /> Any type of number except dollar values-&gt; Stores measurements, counts, and percentages-&gt;<br /></li><li>Currency<br />Similar to Number, but optimized for numbers that represent values of money-&gt;<br />Examples:<br />Prices, payments, and expenses-&gt;<br /></li><li>Date/Time<br />A calendar date or time of day (or both)-&gt; Don&amp;apos;t use this field for time intervals (the number of minutes in a song, the length of your workout session)instead, use the Number data type-&gt;<br />Examples:<br /> Birthdates, order dates, ship dates, appointments, and UFO sighting times-&gt;<br /></li><li>Yes/No<br />Holds one of two values: Yes or No-&gt; (You can also think of this as True or False-&gt;)<br />Examples:<br />Fields with exactly two options, like male/female or approved/unapproved-&gt;<br /></li><li>Hyperlink<br />A URL to a Web site, an email address, or a file path-&gt;<br />Examples:<br />www-&gt;FantasyPets-&gt;com, noreplies@antisocial-&gt;co-&gt;uk, f:DocumentsReport-&gt;doc-&gt;<br /></li><li>Attachment<br />One or more separate files-&gt; The content from these files is copied into the database-&gt;<br />Examples:<br />Pictures, Word documents, Excel spreadsheets, sound files, and so on-&gt;<br /></li><li>AutoNumber<br />Stores a number that Access generates when you insert a new record-&gt; Every record automatically gets a unique number that identifies it-&gt;<br />Examples:<br />Used to uniquely identify each record, especially for a primary key-&gt; Usually, the field&amp;apos;s named ID-&gt;<br /></li><li>OLE Object<br />Holds embedded binary data, according to the Windows OLE (object linking and embedding) standard-&gt; Rarely used, because it leads to database bloat and other problems-&gt; The Attachment field&amp;apos;s almost always a better choice-&gt;<br />Examples:<br />Some types of pictures and documents from other programs-&gt; Mostly used in old-school Access databases-&gt; Nowadays, database designers use the Attachment data type instead of the OLE Object data type-&gt;<br /></li><li>Lecture #2 (11/25/09)<br /></li><li>Activity 1-&gt;2<br />(20 minutes)<br /></li><li>Instructions<br />Get the write-up/summary of the resources and their ease of use-&gt;<br />Group yourselves such that each contains at least 5 members and at most 7-&gt;<br />Select a group leader/scribe-&gt;<br />In the group, each individual must read/share his/her experience searching for information from printed media, then from the internet-&gt; (Guide questions will be given)<br />The scribe should list down the member’s good and bad experiences in using this different media-&gt;<br />After this, the group will summarize all the responses-&gt; And the group leader will then report the summarized responses-&gt;<br /></li><li>Guide Questions for activity<br />Is it easy, or hard to find information from a printed media? <br />In your experience using this media, site the pros and cons of using this media-&gt;-&gt;<br />Is it easy, or hard to find information from the Internet? <br />In your experience using this media, site the pros and cons of using this media-&gt;-&gt;<br />Which is easiest to use when it comes to gathering information-&gt; Why?<br /></li><li>Activity #2 (10-15 min)<br />Take out your mobile phones and get a piece of paper-&gt;<br />From your message inbox count the number of messages you received from:<br />Yesterday<br />Last three days<br />Last week<br />Whole month of November<br /> and list them down in your paper<br />(Dare: In your contacts directory, count the number of persons having 0928 in their mobile number-&gt;<br />Was it easy doing the activity? If not, why?<br /></li><li>Information Management<br />The collectionand managementof information from one or more sources and the distributionof that information to one or more audiences-&gt; This sometimes involves those who have a stake in, or a right to that information-&gt; <br />Managementmeans the organization of and control over the structure, processing and delivery of information-&gt;<br />Information management entails organizing, retrieving, acquiring and maintaining information<br />(http://www-&gt;managing-information-&gt;org-&gt;uk/summary-&gt;htm)<br /></li><li>Laboratory <br />Dec-&gt; 7, 2009<br /></li><li>Common Data Properties of MS Access ‘07<br /></li><li>Field Size (Text length)<br />Every text field has a maximum length-&gt; Text can take up to 255 maximum len<br />The maximum length determines how densely Access can pack your records together-&gt;<br />To set a maximum length, choose your field, and then click the Field Size box in the Field Properties list-&gt; <br />When you click a field property box, that field property&amp;apos;s description appears on the right-&gt;<br /></li><li>Maximum Length Guidelines<br />Here are some recommended maximum lengths:<br />First names and last names – 25 characters handles a first name, while 50 characters each plays it safe for a long, hyphenated last name-&gt;<br />Middle initial – One character-&gt;<br />Email address – Go with 50 characters-&gt; <br />Cities, states, countries, and other places – 50 is enough for most practical purposes-&gt; <br />Street address – A street address consists of a number, followed by a space, then the street name, another space, and the street abbreviation (like Rd or St)-&gt; 50 characters handles it, as long as you put postal codes, cities, and other postal details in other fields-&gt;<br />Phone numbers, postal codes, credit card numbers, and other fixed-length text – Count the number characters and ignore the placeholders, and set the maximum to match-&gt; <br />Description or comments-&gt; 255 characters fits three or four average sentences of information-&gt; If you need more, consider the memo data type instead-&gt;<br /></li><li>Field Size (Numbers)<br />Numbers are divided into several subgroups, the field size depends on whether or not they support fractional values (numbers to the right of a decimal point) and how many bytes of space Access uses to store them-&gt;<br /></li><li>Field Size Options for the Number Data Type-&gt;<br />Field Size: Byte<br />Contains: An integer (whole number) from 0 to 255-&gt; Requires just one byte of space-&gt;<br />When to Use It?<br />This size is risky, because it fits only very small numbers-&gt; Usually, it&amp;apos;s safer to use Integer for small numbers and give yourself a little more breathing room-&gt;<br /></li><li>Field Size Options for the Number Data Type-&gt;<br />Field Size: Integer<br />Contains: Whole number from -32,768 to 32,767-&gt; Requires two bytes of space-&gt;<br />When to Use It?<br /> Useful if you need small numbers with no decimal part-&gt;<br /></li><li>Field Size Options for the Number Data Type-&gt;<br />Field Size: Long Integer<br />Contains: Whole number from <br /> -2,147,483,648 to 2,147,483,647-&gt; Requires four bytes of space-&gt;<br />When to Use It?<br /> The Access standard-&gt; A good choice with plenty of room-&gt; Use this to store just about anything without hitting the maximum, as long as you don&amp;apos;t need decimals-&gt;<br /></li><li>Field Size Options for the Number Data Type-&gt;<br />Field Size: Single<br />Contains: Positive or negative numbers with up to 38 zeroes and 7 decimal places of accuracy-&gt; Requires four bytes of space-&gt;<br />When to Use It?<br /> The best choice if you need to store fractional numbers or numbers that are too large to fit in a Long Integer-&gt;<br /></li><li>Field Size Options for the Number Data Type-&gt;<br />Field Size: Double<br />Contains: Positive or negative numbers with up to 308 zeroes and 15 decimal places of accuracy-&gt; Requires eight bytes of space-&gt;<br />When to Use It?<br /> Useful if you need ridiculously big numbers<br /></li><li>Field Size Options for the Number Data Type-&gt;<br />Field Size: Decimal<br />Contains: Positive or negative numbers with up to 28 zeroes and 28 decimal places of accuracy-&gt; Requires eight bytes of space-&gt;<br />When to Use It?<br /> Useful for fractional numbers that have lots of digits to the right of the decimal point-&gt;<br /></li><li>Format Property (Formatted Text)<br />MS Access allows formatting of texts to allow <br />You can use special symbols in the setting for the Format property to create custom formats for Text and Memo fields-&gt;<br /></li><li>Setting Text Formats<br />You can create custom text and memo formats by using the following symbols:<br />Symbol Description <br />@ Text character (either a character or a space) is required-&gt; <br />&amp; Text character is not required-&gt; <br />&amp;lt; Force all characters to lowercase-&gt; <br />&amp;gt; Force all characters to uppercase-&gt;<br /></li><li>Setting Text Formats<br />Custom formats for Text and Memo fields can have up to two sections-&gt; Each section contains the format specification for different data in a field-&gt;<br />Section Description <br />First Format for fields with text-&gt; <br />Second Format for fields with zero-length strings and Null values-&gt;<br />zero-length string: A string that contains no characters-&gt; You can use a zero-length string to indicate that you know no value exists for a field-&gt; You enter a zero-length string by typing two double quotation marks with no space between them (&amp;quot; &amp;quot;)-&gt;<br />Null: A value you can enter in a field or use in expressions or queries to indicate missing or unknown data-&gt; In Visual Basic, the Null keyword indicates a Null value-&gt; Some fields, such as primary key fields, can&amp;apos;t contain Null-&gt;<br /></li><li>Number formatting<br />The Field Size determines how Access stores your number in the table-&gt; However, you can still choose how it&amp;apos;s presented in the datasheet-&gt; For example, 50, 50-&gt;00, 5E1, $50-&gt;00, and 5000% are all the same number behind the scenes, but people interpret them in dramatically different ways-&gt;<br /></li><li>Number Format Options<br />General Number-&gt; Displays unadorned numbers, like 43-&gt;4534-&gt; Any extra zeroes at the end of a number are chopped off (so 4-&gt;10 becomes 4-&gt;1)-&gt;<br />Currency and Euro-&gt; Both options display numbers with two decimal places, thousands separators (the comma in $1,000-&gt;00), and a currency symbol-&gt; These choices are used only with the Currency data type-&gt;<br />Fixed-&gt; Displays numbers with the same number of decimal places, filling in zeroes if necessary (like 432-&gt;11 and 39-&gt;00)-&gt; A long column of numbers lines up on the decimal point, which makes your tables easier to read-&gt;<br />Standard-&gt; Similar to Fixed, except it also uses thousands separators to help you quickly interpret large numbers like 1,000,000-&gt;00-&gt;<br /></li><li>Number Format Options<br />Percent-&gt; Displays fractional numbers as percentages-&gt; For example, if you enter 0-&gt;5, that translates to 50%-&gt;<br />Scientific-&gt; Displays numbers using scientific notation, which is ideal when you need to handle numbers that range widely in size (like 0-&gt;0003 and 300)-&gt; Scientific notation displays the first non-zero digit of a number, followed by a fixed number of digits, and then indicates what power of ten that number needs to be multiplied by to generate the specified number-&gt; For example, 0-&gt;0003 becomes 3-&gt;00 x 10-4, which displays as 3-&gt;00E-4-&gt; The number 300, on the other hand, becomes 3-&gt;00 x 102, or 3E2-&gt;<br /></li><li>Custom Formatted Numbers<br />This is a cryptic code that tells Access exactly how to format a number-&gt; You need to type the format string you need into the Format box-&gt; For example, if you type in the code #,##0, (including the comma at the end) Access hides the last three digits of every number, so 1 million appears as 1,000 and 15,000 as 15-&gt;<br />Custom number formats can have one to four sections with semicolons (;) as the list separator-&gt; Each section contains the format specification for a different type of number-&gt;<br /></li><li>Parts of Custom Formats<br />Section Description <br /> First The format for positive numbers-&gt; <br />Second The format for negative numbers-&gt; <br />Third The format for zero values-&gt; <br />Fourth The format for Null (Null: A value you can enter in a field or use in expressions or queries to indicate missing or unknown data-&gt; In Visual Basic, the Null keyword indicates a Null value-&gt; Some fields, such as primary key fields, can&amp;apos;t contain Null-&gt;) values-&gt;<br /></li><li>Symbols used-&gt;<br />Symbol Description <br />-&gt; (period) Decimal separator-&gt; Separators are set in the regional settings in Windows-&gt; <br />, (comma) Thousand separator-&gt; <br />0 Digit placeholder-&gt; Display a digit or 0-&gt; <br /># Digit placeholder-&gt; Display a digit or nothing-&gt; <br />$ Display the literal character &amp;quot;$&amp;quot;-&gt; <br />% Percentage-&gt; The value is multiplied by 100 and a percent sign is appended-&gt; <br />E– or e– Scientific notation with a minus sign (–) next to negative exponents and nothing next to positive exponents-&gt; This symbol must be used with other symbols, as in 0-&gt;00E–00 or 0-&gt;00E00-&gt; <br />E+ or e+ Scientific notation with a minus sign (–) next to negative exponents and a plus sign (+) next to positive exponents-&gt; This symbol must be used with other symbols, as in 0-&gt;00E+00-&gt;<br /></li><li>Date &amp; Time Formats<br />Access uses the Date/Time data type to store a single instant in time, complete with the year, month, day, and time down to the second-&gt; <br />Behind the scenes, Access stores dates as numbers, which lets you use them in calculations-&gt;<br /></li><li>Date/Time Formats<br />FormatExample<br />General Date 2/23/2008 11:30:15 PM<br />Long Date February 23, 2008 11:30:15 PM<br />Medium Date 23-Feb-08<br />Short Date 2/23/2008<br />Long Time 11:30:15 PM<br />Medium Time 11:30 PM<br />Short Time 23:30<br /></li><li>Using AutoNumbers without revealing the size of your table<br />Random AutoNumber value-&gt; To use, change the New Values field property from Increment to Random-&gt; <br />Replication IDs-&gt; Replication IDs are long, obscure codes like 38A94E7B-2F95-4E7D-8AF1-DB5B35F9700C that are statistically guaranteed to be unique-&gt; To use them, change the Field Size property from Long Integer to Replication ID-&gt; <br /></li><li>Activity<br />Create a database for a given Company XYZ, having the following tables Products, Manager, Customer representing the actual persons or objects-&gt; <br />Give each tables fields/characteristics, needed in a Business Transaction-&gt;<br />Give each field its necessary type and format-&gt;<br /></li><li>Input Masks<br />An input mask is a set of literal characters and mask characters that control what you can and cannot enter in a field-&gt;<br /></li><li>Components of an Input Mask<br />First Section (Mandatory) – consists of placeholders and literal characters, which make up the mask-&gt;<br />Second Section(Optional) – defines whether you want to store the mask characters and any data in your database-&gt; (0 to store mask and data, 1 to store the data only)<br />Third Section (Optional) – defines the placeholder that is used to indicate positions for the data-&gt; (By default, Access uses the underscore (_)-&gt;<br /></li><li>Input Mask Character Reference<br /></li><li>Input Mask Character Reference(continued…)<br /></li><li>Input Mask Character Reference(continued…)<br /></li>