怎样将EXCEL表格数据通过C#.NET导入到SQL数据库中？

你完全可以把Excel当数据表一样读出来，然后再写进Sql
读Excel的方法：
string strConn = "provider=Microsoft.Jet.OLEDB.4.0;data source=Excel文件;Extended Properties=Excel 8.0;";

OleDbConnection oleConn = new OleDbConnection(strConn);
oleConn.Open();
string olestr = "select * from [Sheet1$]";
OleDbCommand oleComm = new OleDbCommand(olestr, oleConn);
oleComm.Connection = oleConn;
OleDbDataAdapter oleDa = new OleDbDataAdapter();
oleDa.SelectCommand = oleComm;
DataSet ds = new DataSet();
oleDa.Fill(ds);
foreach (DataRow row in ds.Tables["INFO"].Rows)
{
string userInfo = row[0].ToString().Trim();
}
oleConn.Close();

给你写个思路吧。
FileStream fs=File.Open("C:\\bb.xls",FileMode.Open);
byte[] by=new byte[fs.Length];
fs.Read(by,0,(int)fs.Length);
String SqlCmd = "UPDATE 表 SET 字段=(@Image) where ....";
SqlCommand CmdObj = new SqlCommand(SqlCmd, conn.myConnection);
CmdObj.Parameters.Add("@Image",SqlDbType.Binary, (int)fs.Length).Value = by;
fs.Close();
CmdObj.ExecuteNonQuery();