Sure, you can use an existing stored procedure as long as it provides the necessary data. Having more columns will not hurt. Make sure that you populate correctly the ChartSeries' properties that define ChartSeriesItems' values -- DataLabelsColumn, DataXColumn, DataYColumn, DataXColumn2, DataYColumn2, DataYColumn3 and DataYColumn4 (use only those that are relevant for your series).
As a side note, RadChart is not in active development and for new development we recommend using our RadHtmlChart
. You can find a detailed comparison here
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