How can I allow uploading and mapping of Excel file to relational database?

I've seen some online control panels where you can upload a delimited file, then it takes you to a screen where you can map the column headers of the delimited file to the database column names. How can I do this so I can allow uploading of an Excel file, then the page lists the column headers with a dropdown to the database table columns next to it? I intend on saving that "mapping" to an XML file. I'm using this with an MS SQL 2008 and Access 2007 database. Has anyone done anything like this before?
bemara57Asked:
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jvullietConnect With a Mentor Commented:
Hello,

you can also use OleDb to access your excel file like a database.

Had to make something similar for a project, so wrote a little help class, see code snippet below.

Code is quite self explanatory, but if you need more help don't hesitate to ask.

using System;
using System.Collections.Generic;
using System.Text;
using System.Data.OleDb;
using System.Data;
 
namespace ExcelUtils
{
    public class ExcelFacility
    {
        private string filename;
        private OleDbConnection cnx;
 
        private OleDbConnection getConnection()
        {
            if (cnx == null)
            {
                cnx = new OleDbConnection();
                cnx.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + filename + ";Extended Properties=" + (char)34 + "Excel 8.0;HDR=Yes;" + (char)34;
            }
            return cnx;
        }
 
        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="filename">Excel file to process</param>
        public ExcelFacility(string filename)
        {
            this.filename = filename;
        }
 
        #region List Tables from spreadsheet
        public List<string> ListTables()
        {
            cnx = getConnection();
            List<string> res = new List<string>();
            try
            {
                cnx.Open();
                DataTable tbl = cnx.GetSchema("Tables");
                foreach (DataRow row in tbl.Rows)
                {
                    res.Add(row["TABLE_NAME"].ToString());
                }
                cnx.Close();
                return res;                
            }
            catch 
            {
                cnx.Close();
                throw;
            }
        }
        #endregion
 
        #region List Columns
        public List<string> ListColumns(string table)
        {
            cnx = getConnection();
            List<string> res = new List<string>();
            try
            {
                cnx.Open();
                DataTable tbl = cnx.GetSchema("COLUMNS");
                foreach (DataRow row in tbl.Rows)
                {
                    if (row["TABLE_NAME"].ToString() == table)
                    {
                        res.Add(row["COLUMN_NAME"].ToString());
                    }
                }
                cnx.Close();
                return res;
            }
            catch
            {
                cnx.Close();
                throw;
            }
        }
        #endregion
 
        #region Get Data in Datatable
        public DataTable GetData(string tbl)
        {
            try 
            {
                string sql = "Select * from [" + tbl + "]";
                OleDbDataAdapter da = new OleDbDataAdapter(sql, getConnection());
                DataSet dst = new DataSet();
                da.Fill(dst);
                cnx.Close();
                return dst.Tables[0];
            } 
            catch 
            {
                cnx.Close();
                throw;
            }
        }
        #endregion
    }
}

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REA_ANDREWCommented:
Does the file have to be XLS or will or could be CSV.  There may be a license aspect if you want to parse XLS as you need to use Interop and I think you would need a server license for MS OFFICE.  Not sure, but that is what I think.

XLS requires you use the .NET Interop library for excel in office
CSV, is simple string parsing and the top line are generally your headers.

Andrew
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Mark WillsTopic AdvisorCommented:
Yep,

can connect to it via a linked server - each table page is then available as if it were a "table"  (advantage can update the spreadsheet)
can connect with openrowset (advantage can manipulate each column as you read it)
can connect with openquery (similar to above)

examples below...  Not exactly sure what the column names with a dropdown is all about - might want to describe that a bit more, along with the XML mapping.



--1) LINKED SERVER
 
-- create a link to that spreadsheet so we can import
EXEC sp_addlinkedserver MyExcel,
     'Jet 4.0',
     'Microsoft.Jet.OLEDB.4.0',
     'c:\ee\My_Test_Spreadsheet.xls', 
      NULL,
     'Excel 5.0;'
GO
 
--Set up login mappings (just ADMIN - jet wants something).
EXEC sp_addlinkedsrvlogin MyExcel, FALSE, NULL, Admin, NULL
GO
 
--List the tables in the linked server (these are the worksheet names) - not needed, but interesting
EXEC sp_tables_ex MyExcel
GO
 
-- now just to make sure we can see the "real" stuff...
select * from myexcel...sheet1$ 
 
-- we can also write back / update that spreadsheet from here just like a table.
 
-- now clean it up...
sp_dropserver 'MyExcel', 'droplogins';
GO
 
 
 
--2) OPENROWSET
 
-- or use openrowset
SELECT * FROM OPENROWSET('Microsoft.Jet.OLEDB.4.0', 'Excel 8.0;Database=c:\ee\My_Test_Spreadsheet.xls;HDR=YES', 'SELECT * FROM [sheet1$]')
GO
 
 
--1) OPENDATASOURCE
 
-- or use opendatasource
select * from OPENDATASOURCE('Microsoft.Jet.OLEDB.4.0', 'data source="c:\ee\My_Test_Spreadsheet.xls";Extended properties=Excel 5.0;')...[sheet1$] 
GO

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bemara57Author Commented:
Thanks for that the help. jvulliet, your script seems like the one I need, but I'm having a run-time error when I try to load up ListColumns(table) into a Grid. My worksheet is called "Worksheet1", so I'm calling ListColumns("Worksheet1$"), but I get this error:

The Microsoft Jet database engine could not find the object ''Worksheet1$'_'.  Make sure the object exists and that you spell its name and the path name correctly.

Do you know what this error means?
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jvullietCommented:
Hello, I think you just have to use ListColumns("Worksheet1")  if i remember well.
Does ListTables() works by the way?
Could just be a version issue otherwise (need to change the connection string).
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bemara57Author Commented:
That's what I initially tried (without the $ at the end), but gave me the identical error:

The Microsoft Jet database engine could not find the object ''Worksheet1$'_'.  Make sure the object exists and that you spell its name and the path name correctly.

Yes, ListTables() work and I get this in the Grid:
-------------------
Item
-------------------
Database
'Worksheet1$'
'Worksheet1$'_

Also, GetData("Worksheet1$") works and populates the Grid with all the records, but GetData("Worksheet1") crashed saying that it can't find the object.

I've read so much confusion about why there are multiple names for the same tab in Excel. I only have one tab worksheet in it.
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