Checking if specific columns data exists in a different workbook c# ..

Question

I've got a couple of different workbooks 1) newData.xlsx & 2) DATABASE.xlsx (image and file attached below)

I'm trying to check whether the Bill No. & Bill Date of the first row (i.e. row 6, as the relevant data starts from row 6) & last rows of the newData.xlsx file already exist in the DATABASE.xlsx file. The column numbers of both the target cells are different in both files.

 

How can I do this in the most efficient way possible using spire.xls & c#?

 

I've tried the below

string queryFrom=@"D:\sample\newData.xlsx";
string queryIn=@"D:\sample\Testing\DATABASE.xlsx";
Workbook workbook = new Workbook();
workbook.LoadFromFile(queryFrom);
Worksheet sheet = workbook.Worksheets[0];
var firstRowCellBillNo=sheet.Range["M6"].Value2.ToString().Trim();
var firstRowCellBillDate=sheet.Range["N6"].Value2.ToString().Trim();
var lastRowCellBillNo=sheet.Range["M"+(sheet.LastRow - 1)].Value2.ToString().Trim();
var lastRowCellBillDate=sheet.Range["N"+(sheet.LastRow - 1)].Value2.ToString().Trim();
Dictionary<string, string> dictionary = new Dictionary<string, string>();
Dictionary<string, string> dictionary2 = new Dictionary<string, string>();
if (!dictionary.ContainsKey(firstRowCellBillNo) && !dictionary.ContainsKey(lastRowCellBillNo))
{
        dictionary.Add(firstRowCellBillNo.ToString(), firstRowCellBillDate.ToString());
        dictionary.Add(lastRowCellBillNo.ToString(), lastRowCellBillDate.ToString());
}
workbook.Dispose();
Workbook wbk=new Workbook();
wbk.LoadFromFile(queryIn);
Worksheet sh=wbk.Worksheets[0];
CellRange xlRange=sh.Range[1,1,sh.LastRow,sh.LastColumn];
int rowCount = xlRange.RowCount;
for (int i = 1; i < rowCount; i++)
{
        var col1 = xlRange.Columns[4].CellList[i].Value2.ToString();
        var col2 = xlRange.Columns[5].CellList[i].Value2.ToString();
        if (!dictionary2.ContainsKey(col1))
        {
                dictionary2.Add(col1.ToString(), col2.ToString());
        }
}
//If ( the key value pair's of dictionary exist in dictionary2 )
{
        Console.WriteLine("Data already exists in database!!");
}
//Else
{ Do some stuff }
wbk.Dispose();

I think my above code approach is complicating things and not to mention unfinished.

 

Can anyone help me on this?

 

1st image newData.xlsx and 2nd image DATABASE.xlsx