使用C# Oledb 过滤excel电子表格并返回特定值

Question

I have a WPF app of which I would like to pull specific data from based on two variables. The data source is the below spreadsheet, there are no specific settings applied it is simply raw data.

I would like a method of which I could call ie;

GetValue("A", "Dec-19")

With:

GetValue(string Product, DateTime Date)

This would return the value 0. I have tried numerous approaches however am unable to produce anything that functions. Here is a variation of an attempt of mine I was working on;

public double GetValue(string type, OleDbConnection TargetBuildOleDbConnection, DateTime Selection)
{
    string date = Selection.ToString("MMM-yy", ci);
    string CustomQuery = "SELECT ['" + date + "'] FROM [SHEET1$A1:Z1] WHERE [Product] = '" + type + "'";
    using (DataTable dt = new DataTable())
    {
        using (DataView dv = new DataView(dt))
        {
            using (OleDbCommand comm = new OleDbCommand())
            {
                comm.CommandText = "Select * from [Build Schedule$]";
                comm.Connection = TargetBuildOleDbConnection;
                using (OleDbDataAdapter da = new OleDbDataAdapter())
                {
                    da.SelectCommand = comm;
                    da.Fill(dt);

                }
            }
            dv.RowFilter = "SELECT ['" + date + "'] FROM [SHEET1$A1:Z1]"; //throwing exception
            double target = dt.Rows[0].Field<int>(0);
            return target;
        }
    }
}

Answer 1

This is a modified version of your original code that will hopefully accomplish what you were looking for:

public double GetValue(string product, OleDbConnection targetBuildOleDbConnection, DateTime dte)
{
    const double defaultValue = 0; // Value to return if no match is found

    const string prodParamName = "@prod";

    using (OleDbCommand comm = new OleDbCommand())
    {
        comm.Connection = targetBuildOleDbConnection;
        comm.CommandText = string.Format("SELECT * FROM [Build Schedule$] WHERE Product={0}", prodParamName);
        comm.Parameters.Add(prodParamName, OleDbType.VarWChar); // Maybe VarChar is good enough (?)
        comm.Parameters[prodParamName].Value = product;

        using (OleDbDataReader rdr = comm.ExecuteReader())
        {
            if (!rdr.Read()) return defaultValue;

            for (var i = 1; i < rdr.FieldCount; i++)
            {
                var colName = rdr.GetName(i);

                double colNumber;
                if (double.TryParse(colName, out colNumber)) // If the date headers have actual Excel dates
                {
                    DateTime colDate = DateTime.FromOADate(colNumber); // Convert Excel's date number to a C# date
                    if (colDate.Month != dte.Month || colDate.Year != dte.Year) continue;
                }
                else if (colName != dte.ToString("MMM-yy")) // If the date headers are actual Excel strings
                    continue;

                double colValue;
                if (double.TryParse(rdr.GetValue(i).ToString(), out colValue)) return colValue;

                break; // No point in continuing, since we found the right column, but it did not have a valid double
            }
        }

        return  defaultValue;
    }
}

Please note the following:

• The code assumes the data is on a sheet called "Build Schedule"
• The code does not use the ci CultureInfo variable you used in the ToString call because I did not know where that variable came from
• Since the function is of type double , it returns 0, instead of null, if no matching value is found; if you prefer null in these cases, the function can be changed to type double? , but the code that calls this function must be aware that a null can be returned
• The code should theoretically work whether the date header cells (eg the "Nov-19" and "Dec-19" cells) contain date values that are merely formatted as "MMM-yy" in Excel or whether they contain actual strings; you may want to eliminate either the if or the else block inside the for loop if you only want to handle one case
• The code does not take advantage of certain syntax improvements in recent versions of C# (in case you are using an older version)
• The search for the right column can be optimised, especially if this function will be called many times in consecutive fashion

I tested this code, and it seemed to return the right value every time. I hope it works for you.