Working with Databases in Microsoft Excel

Transcription

1 Working with Databases in Microsoft Excel

2 Creating a new database in Excel A database is an organized set of information. It can contain anything from the phone numbers in a rolodex to the data from a research project. The typical database (Excel calls it a 'list') uses the columns in a worksheet for the different pieces of information, also called data elements or fields. The names of the fields are usually entered on row 1 of the worksheet. Each row after 1 holds the data for one subject or case in the database. Working with databases involves two sets of activities. The first set of activities involves creating the structure of the database and entering the data into it with as few errors as possible. The second set of activities involves reporting activities, or extracting information from the database. This exercise focuses on the first set of activities involved in creating a database.

3 Start a new workbook for the exercise Open a new workbook in Microsoft Excel. If it has less than 2 worksheets, add worksheets to it. To rename the workbook and save it in a directory where we can later find it, we complete the specifications in the Save As dialog box. We will name the workbook AgencyClients.xls and save it in the StudentData folder. on the C:\ hard drive. Creating Databases, Slide 3

4 Specify the directory and name for the file First, if necessary, navigate to the directory C:\StudentData. When the file is saved, the dialog box will close and the new file name will be shown in the window title bar. Second, we type the name of the file in the File name text box, AgencyClients.xls. Third, click on the Save button to save the workbook in a file that has the new name. Creating Databases, Slide 4

5 Change the name of Sheet1 to Demographics When an application has multiple worksheets, giving the worksheets meaningful names makes it easier to keep track of what we are doing. To change the name of Sheet1 to Demographics, select the Sheet Rename command from the Format menu. Creating Databases, Slide 5

6 Type the new name for the worksheet With the old name for the worksheet highlighted, we type Demographics, followed by the Enter key to replace the old name with the new name. Creating Databases, Slide 6

7 Enter the field names for the columns in the database Type the descriptive field names for this data set in the first row of the worksheet. Type 'ID Number' in cell A1, 'Sex' in cell B1, 'Birth Date' in cell C1, and 'Marital Status' in cell D1. Creating Databases, Slide 7

8 Adjust width of columns so field names are fully visible First, drag select columns A through D by clicking on the column letter A and dragging through the column letter D. Second, select the Column Autofit Selection command from the Format menu. Part of the text of the field names is not visible because the columns are not wide enough to display the contents. We can adjust the widths of all of the columns so they are large enough to display their contents. Creating Databases, Slide 8

9 Freeze the field names so that they stay on the screen After we have typed in seventeen rows of data, the field names will scroll off the screen when we go to row 18. We can prevent this by freezing their position on the worksheet. First, to freeze the field names, we highlight the row beneath the row that we want to freeze. Click on row number 2 to select the entire row. Second, we select the Freeze Panes command from the Window menu. Creating Databases, Slide 9

10 The worksheet with a frozen field name pane The only visible change that the frozen pane makes on the worksheet is the solid line beneath the frozen row holding the field names. We can now scroll past the rows on the first screen without the field names disappearing from the worksheet. Creating Databases, Slide 10

11 Validating data entries in a database Reporting on databases assumes that all the data was entered correctly, an assumption that is not usually warranted because errors in data entry are inevitable. There are two strategies for reducing errors in data entry. One is redundancy, in which we enter the same data twice on two different worksheets and compare the entries cell by cell. If both cells for an item agree, we conclude that the data is correct. If the cells disagree, we decide which one is in error and make a correction. Redundant data entry is expensive; we are doing the same task twice. To try to avoid this replication, we can attempt to validate our data entry as we go along. Validation involves checking a user's answers as we go along, or letting the user select from a fixed list of choices so that they cannot mistype an entry. In this exercise, we will add data validation to our database.

12 Validation for the numeric variable ID Number To validate the data for a field or column, we first click on the column letter to highlight the entire column. Second, we select the Validation command from the Data menu. Creating Databases, Slide 12

13 Selecting Whole number as the type of value for ID Number The specification for ID Number is that it be a four digit number. Decimals are not permitted. To specify this requirement, we select 'Whole number' form the 'Allow' drop down list. Creating Databases, Slide 13

14 Specifying relationship for acceptable values of ID Number The specification for a four digit number implies that the ID Number be a number between 1000 and We specify this with the between relationship from the Data drop down list. Creating Databases, Slide 14

15 Specifying the range of acceptable values for ID Number Fourth, when we have completed the specifications for ID Number completed, we click on the Input Message tab to complete that item. With the between relationship selected, we first enter 1000 in the Minimum value text box. Third, we do not want a user to leave ID Number blank, so we clear the Ignore Blank checkbox. Second, we enter 9999 in the Maximum value text box. Creating Databases, Slide 15

16 Entering the Input Message for ID Number The 'Input Message' is a prompt or instruction that will appear when the user selects a cell in this column for data entry. The 'Input Message' has two parts: a title and a message. First, we click on the Input Message tab to navigate to that page. Second, we type the title which is the first line of the message, printed in bold type. Type in the name of the field 'ID Number'. Third, we type in a message that informs the user what they are expected to enter, in this case 'Enter a four digit number'. Fourth, when our input message is complete, click on the Error Alert tab to specify the computers response when the user enters incorrect data. Creating Databases, Slide 16

17 The Error Alert for an incorrect ID Number The error alert specifies the feedback given to the user when they have typed an incorrect entry. We can select a style for the dialog box that contains the feedback. Style controls the options the user is given when an incorrect entry is displayed. The 'Stop' style requires the user to retype the entry. The 'Warning' and 'Information' styles inform the user of the mistake, but allow the incorrect data to remain in the cell. The 'Title' and 'Error message' text boxes contain the text of the feedback to the user. Creating Databases, Slide 17

18 Entering the Error Alert for an incorrect ID Number First, click on the Error Alert tab to navigate to that page. Third, we type in the Title of the window in which the alert message appears. We will use the name of the field: 'ID Number'. Second, we select the 'Stop' style for the alert box. Fifth, we click on the OK button to conclude our Data Validation entry. Fourth, we type in the Error message which tells the user what to do to correct the error: 'The ID Number is the four digit number in the upper right hand corner of page 1 of the questionnaire' Creating Databases, Slide 18

19 Remove the validation for the ID Number field name To remove the validation for a cell, we first click on the cell to select it. Then, we select the Validation command from the Data menu. Creating Databases, Slide 19

20 Clear the validation from cell A1 First, click on the Clear All button in the lower lefthand corner of the dialog box. It does not matter which page we are on in the dialog box. Second, click on the OK button to complete the action. Creating Databases, Slide 20

21 Displaying the input prompt for ID Number When we select a cell, e.g. A2, in the ID Number column, the Input Message prompt appears. Creating Databases, Slide 21

22 Entering a correct ID Number When we enter a correct ID Number, e.g. 1001, and press the enter key, Excel checks our input against the validation criteria. If our entry passes the test, Excel advances us to the next cell. Creating Databases, Slide 22

23 Entering an incorrect ID Number When we enter an incorrect number for ID, e.g. 101 which is not between 1000 and 9999, Excel displays our Error Alert message. We click on the Retry button and correct our entry. Creating Databases, Slide 23

24 'Blanks' as a data entry error We cleared the checkbox 'Ignore blank' as a data validation setting because we did not the user to leave an ID Number blank. This option does not appear to work as expected, because the definition of what is a blank is ambiguous. If a user navigates to a new cell with the Enter or arrow keys, no error message appears. If the user types blank spaces in the cell (by pressing the spacebar), an error message will appear. This error message appears because Excel's validation for this cell converts the blanks to a number, decides they equal zero, and finds that zero is outside the range from 1000 to If the user deletes the blanks spaces, Excel will permit the user to go to the next cell. While I am certain that there are logical and reasonable explanations for this behavior, it does pose the problem for us of how to detect cells that were inadvertently left blank or empty. The answer lies in Excel's auditing tool.

25 Leaving cells blank to test the auditing tool First, we deliberately leave cell A3 blank and enter correct data, e.g. 1003, in cell A4. Second, we select the Show Formula Auditing Toolbar command from the Tools Formula Auditing menu. Creating Databases, Slide 25

26 Circling invalid entries to detect data entry errors The Formula Auditing tool bar is activated. Click on the Circle Invalid Data tool button. Creating Databases, Slide 26

27 Excel limits the number of errors it will show Since we set ID Number validation for the entire column A, Excel checks the entire column. When it gets to 255 errors, it displays an error message. Creating Databases, Slide 27

28 Excel correctly detects the blank in cell A3 Our purpose in auditing the worksheet was to detect the blank cell A3 as an error. Excel has correctly circled A3. We should ignore all of the other red circles as extraneous information. To remove the red auditing circles, click on the 'Clear Validation Circles' tool button. To remove the auditing tool bar, click on its 'Close' box. To remove the red auditing circles, click on the Clear Validation Circles tool button. To remove the auditing tool bar, click on its Close box. Creating Databases, Slide 28

29 The red auditing circles are removed Enter correct data, 1002, in cell A3. To close the formula auditing tool bar, click on its Close box. Creating Databases, Slide 29

30 Validation for the text variable sex To validate the data for a field or column, we first click on the column letter to highlight the entire column. Second, we select the Validation command from the Data menu. Creating Databases, Slide 30

31 Select List as the type of data for Sex The acceptable entries for Sex are Male and Female. When we have only a few optional responses, we can use a drop down list for data entry. Select List as the type of data to allow. Creating Databases, Slide 31

32 Specifying the acceptable list options for Sex Second, we mark the Ignore blank checkbox as we will treat blanks as missing data. Since we want a drop down list, we mark the In-cell dropdown checkbox. We first enter the response options as comma separated text, i.e. we type Male and Female in the Source text box, separated by a comma, i.e. Male,Female Third, we click on the Input Message tab to enter specifications for that item. Creating Databases, Slide 32

33 Entering the Input Message for Sex First, we enter the field name Sex in the title which is the first line of the message, printed in bold type. Second, we type in a message that informs the user what they are expected to enter: Select Male or Female from the drop down list Third, since we expect our users to select from a menu, we do not expect them to mistype their entry. We will not include a specific error message. Click on the OK button. Creating Databases, Slide 33

34 Remove the validation for the Sex field name To remove the validation for a cell, we first click on the cell to select it. Then, we select the Validation command from the Data menu. Creating Databases, Slide 34

35 Clear the validation from cell B1 First, click on the Clear All button in the lower left-hand corner of the dialog box. It does not matter which page we are on in the dialog box. Second, click on the OK button to complete the action. Creating Databases, Slide 35

36 Displaying the input prompt for Sex When we select a cell, e.g. B2, in the Sex column, both the arrow for the drop down list and the Input Message prompt appear. Creating Databases, Slide 36

37 Selecting a value for Sex from the drop down list We highlight our choice from the drop down menu and Excel fills in the cell with our choice. Creating Databases, Slide 37

38 The Error Alert for an incorrect entry for Sex If a user types an entry directly in the that does not match a choice on the list, e.g. Man instead of Male, Excel displays its default error message because we did not specify an error alert for this column. Click on Retry and correct the entry. Creating Databases, Slide 38

39 Validation for the date variable Birth Date To validate the data for a field or column, we first click on the column letter to highlight the entire column. Second, we select the Validation command from the Data menu. Creating Databases, Slide 39

40 Select Date as the type of data for Birth Date We want to limit the user's entries for Birth Date to something that Excel can interpret as a date. Select the Date option from the list of allowable values. Creating Databases, Slide 40

41 Specifying the acceptable values of Birth Date First, we specify a between relationship for a range of values. Fourth, we will accept a blank entry as missing data, so we mark the Ignore Blank checkbox. Second, we enter 1/1/1901 in the Start date text box. Fifth, when we have completed the specifications for Birth Date completed, we click on the Input Message tab to complete that item. Third, we enter 12/31/2002 in the End date text box. Creating Databases, Slide 41

42 Entering the Input message for Birth Date The Input Message will appear when the user selects a cell in this column for data entry. First, we click on the Input Message tab to navigate to that page. Fourth, when our input message is complete, click on the Error Alert tab to specify the computers response when the user enters incorrect data. Second, we enter the title, Birth Date which will be first line of the message, printed in bold. Third, we type in a message that informs the user what they are expected to enter: Enter a date between 1/11901 and 12/21/2002 in the format: mm/dd/yyyy Creating Databases, Slide 42

43 Entering the Error Alert for an incorrect Birth Date When the user enters incorrect data, an Error Alert informs them of their error. First, we select the Stop style for the alert box. Third, we type in a message which tells the user what they should do to correct the error: Please enter a date between 1/11901 and 12/21/2002 in the format: mm/dd/yyyy Second, we type in the title of the window in which the alert message appears. Fourth, we click on the OK button to conclude our Data Validation entries. Creating Databases, Slide 43

44 Remove the validation for the field name To remove the validatation for a cell, we first click on the cell to select it. Then, we select the Validation command from the Data menu. Creating Databases, Slide 44

45 Clear the validation from cell C1 First, click on the Clear All button in the lower lefthand corner of the dialog box. It does not matter which page we are on in the dialog box. Second, click on the OK button to complete the action. Creating Databases, Slide 45

46 Entering correct data for Birth Date When we enter a value for Birth Date, Excel checks our answer to see if it passes the validation test. If it does, Excel advances to the next data entry cell. Select cell C2 and enter 12/2/1968 as the birth date. Creating Databases, Slide 46

47 Entering alternative format of correct data for Birth Date When we enter a value for Birth Date, Excel checks the date value, not the formatted value against the validation criteria. Thus, a valid date entered in an incorrect format, like Month Day, Year, will pass the validation test, e.g. March 12, Creating Databases, Slide 47

48 Excel accepts dates in alternate formats Excel accepts anything that it can translate into a date, but it formats it in its default date format. Creating Databases, Slide 48

49 Entering incorrect data for Birth Date An error for Birth Date will be an entry that Excel cannot interpret as a date, for example, a month name such as June. Creating Databases, Slide 49

50 Error response for an incorrect date Excel checked our entry of June against allowable data including possible alternative formats for dates. When it could not make a match, it displayed the error message. We click on the Retry button and correct our entry. Creating Databases, Slide 50

51 Entering incorrect data for Birth Date that Excel accepts If we enter a number like a year, e.g. 1967, Excel accepts it as a valid date. In its way of working with dates, Excel tracks dates as the number of days after January 1, 1900, making 1967 equivalent to May 20, May 20, 1905 falls within our specified range from January 1, 1901 to December 31, 1999, so Excel accepts it as a valid entry. Creating Databases, Slide 51

52 Creating a list of acceptable entries for Marital Status A drop down list may have more entries than can reasonably appear in the Source box for a validation list. In this case, we can enter the alternatives on a section of a worksheet and use that section as the source for the items in a drop down list. First, we navigate to the Sheet2 worksheet and change its name to Codes. Second, we type the response options in cells on this worksheet: type Never Married in cell A1, Married in cell A2, and Divorced in cell A3, Separated in cell A4, and Widowed in cell A5. Creating Databases, Slide 52

53 Naming the list of acceptable entries for Marital Status A worksheet range can only be used as the source for a validation drop down list if it has a name instead of a cell reference. To assign a name to cells A1:A5 on the Codes worksheet, we first highlight the five cells. Second, we select the Name Define command from the Insert menu. Creating Databases, Slide 53

54 Defining the name of the list Second, we type the name MaritalCodes in the text box under the label Names in workbook. First, we check the entry in the Refers to text box at the bottom of the dialog box to make sure it refers to the correct cells. Note: the names cannot contain any blanks Creating Databases, Slide 54

55 The name of the list in the Name Box When the named cells are all highlighted, their name instead of their cell reference will appear in the name box. Creating Databases, Slide 55

56 Validation for the text variable Marital Status First, navigate back to the Demographics worksheet where the data will be entered. Second, we first click on the column letter, D, to highlight the entire column. Third, we select the Validation command from the Data menu. Creating Databases, Slide 56

57 Select List as the type of data for Marital Status The acceptable entries for marital status are: Never Married, Married, and Divorced, Separated, and Widowed. When we have a long list of items like this, we still use list validation, but we populate the list with items entered on a named section of a worksheet. Creating Databases, Slide 57

58 Specifying the acceptable list options for Marital Status We first enter the response options as a reference to a named set of cells in the workbook, i.e. we type =MaritalCodes. Do not forget the equal sign (=) at the beginning of the entry. Second, we mark the Ignore blank checkbox as we will treat blanks as missing data. Since we want a drop down list, we mark the In-cell dropdown checkbox. Third, we click on the Input Message tab to enter specifications for that item. Creating Databases, Slide 58

59 Entering the Input message for Marital Status The Input Message will appear when the user selects a cell in this column for data entry. First, we enter the title, which will be first line of the message, printed in bold. Second, we type in a message that informs the user what they are expected to enter. Third, since we expect our users to select from a menu, we do not expect them to mistype their entry. We will not include a specific error message. Click on the OK button. Creating Databases, Slide 59

60 Remove the validation for the Marital Status field name To remove the validatation for a cell, we first click on the cell to select it. Then, we select the Validation command from the Data menu. Creating Databases, Slide 60

61 Clear the validation from cell D1 First, click on the Clear All button in the lower left-hand corner of the dialog box. It does not matter which page we are on in the dialog box. Second, click on the OK button to complete the action. Creating Databases, Slide 61

62 Displaying the input prompt for marital status When we select a cell, e.g. D2, in the Marital Status column, both the arrow for the drop down list and the Input Message prompt appear. Creating Databases, Slide 62

63 Selecting a marital status from the drop down list We highlight our choice from the drop down menu and Excel fills in the cell with our choice. Creating Databases, Slide 63

64 A marital status in the worksheet The marital status selected from the drop down list is shown in the cell. Creating Databases, Slide 64