Adobe ColdFusion 8

Creating an area chart

The example in the following procedure adds an area chart to the salaries analysis page. The chart shows the average salary by start date to the salaries analysis page. It shows the use of a second query of queries to generate a new analysis of the raw data from the GetSalaries query. It also shows the use of additional cfchart attributes.

  1. Open the chartdata.cfm file in your editor.
  2. Edit the GetSalaries query so that it appears as follows:
    <!-- Get the raw data from the database. -->
<cfquery name="GetSalaries" datasource="cfdocexamples">
    SELECT Departmt.Dept_Name, 
        Employee.StartDate,
        Employee.Salary
    FROM Departmt, Employee
    WHERE Departmt.Dept_ID = Employee.Dept_ID
</cfquery>

  3. Add the following code before the html tag:
    <!--- Convert start date to start year. --->
<!--- You must convert the date to a number for the query to work --->
<cfloop index="i" from="1" to="#GetSalaries.RecordCount#">
<cfset GetSalaries.StartDate[i]=NumberFormat(DatePart("yyyy", GetSalaries.StartDate[i]) ,9999)>
</cfloop>

<!--- Query of Queries for average salary by start year. --->
<cfquery dbtype = "query" name = "HireSalaries">
    SELECT 
        StartDate,
        AVG(Salary) AS AvgByStart
    FROM GetSalaries
    GROUP BY StartDate
</cfquery>

<!--- Round average salaries to thousands. ---> 
<cfloop index="i" from="1" to="#HireSalaries.RecordCount#">
    <cfset HireSalaries.AvgByStart[i]=Round(HireSalaries.AvgByStart[i]/1000)*1000>
</cfloop>

  4. Add the following cfchart tag before the end of the body tag block:
    <!--- Area-style Line chart, from HireSalaries Query of Queries. --->
<cfchart 
        chartWidth=400
        BackgroundColor="##FFFF00"
        show3D="yes"
    >
    <cfchartseries
        type="area" 
        query="HireSalaries" 
        valueColumn="AvgByStart" 
        itemColumn="StartDate"
     />
</cfchart>
<br>

  5. Save the page.
  6. View the chartdata.cfm page in your browser.

Reviewing the code

The following table describes the code and its function:

Code

Description
Employee.StartDate,

Add the employee start date to the data in the GetSalaries query.
<cfloop index="i" from="1" to="#GetSalaries.RecordCount#"> <cfset GetSalaries.StartDate[i]= NumberFormat(DatePart("yyyy", GetSalaries.StartDate[i]) ,9999)> </cfloop>

Use a cfloop tag to extract the year of hire from each employee's hire data, and convert the result to a four-digit number.
<cfquery dbtype = "query" name = "HireSalaries"> SELECT StartDate, AVG(Salary) AS AvgByStart FROM GetSalaries GROUP BY StartDate </cfquery>

Create a second query from the GetSalaries query. This query contains the average salary for each start year.

<cfloop index="i" from="1" to="#HireSalaries.RecordCount#"> <cfset HireSalaries.AvgByStart[i] =Round(HireSalaries.AvgByStart[i] /1000)*1000> </cfloop>

Round the salaries to the nearest thousand.
<cfchart chartWidth=400 BackgroundColor="##FFFF00" show3D="yes" > <cfchartseries type="area" query="HireSalaries" valueColumn="AvgByStart" itemColumn="StartDate" /> </cfchart>

Create a line chart using the HireSalaries query. Chart the average salaries against the start date.

Limit the chart width to 400 pixels, show the chart in three dimensions, and set the background color to white.

Setting curve chart characteristics

Curves charts use the attributes already discussed. However, you should be aware that curve charts require a large amount of processing to render. For fastest performance, create them offline, write them to a file or variable, and then reference them in your application pages. For information on creating offline charts, see Writing a chart to a variable.