Develop Reference

GetOleDbSchemaTable columns slow for large worksheet

I am using the ACE OLEDB connection string to connect to an excel file. I've noticed my query (see example below) that returns the column schema takes longer to run when the worksheet has more rows of data on it.
For some of my larger worksheets (200k rows) it is taking around 10 seconds for the header schema to be returned. It there a way to speed this up or a better way to get the column headers?
string connectionString = string.Empty;
connectionString = String.Format(#"Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};
Extended Properties=""Excel 12.0 Xml;HDR=YES;IMEX=1""", path);
OleDbConnection con = new OleDbConnection(connectionString);
con.Open();
DataTable dtSchema = new DataTable();
System.Diagnostics.Debug.WriteLine("Start: " + DateTime.Now.ToLongTimeString());
dtSchema = con.GetOleDbSchemaTable(OleDbSchemaGuid.Columns,
new Object[] { null, null, WorksheetName, null });
System.Diagnostics.Debug.WriteLine("End: " + DateTime.Now.ToLongTimeString());
con.Close();
UPDATE
I tried rewriting this - turning Headers off and manually reading only the first row. It still takes around 10 seconds to process on my larger files (small ones still come back very quickly). Is there anything else I can try that might be able to get the header(first row) values quicker?
string connectionString = string.Empty;
connectionString = String.Format(#"Provider=Microsoft.ACE.OLEDB.12.0; Data Source={0};
Extended Properties=""Excel 12.0 Xml;HDR=NO;""", path);
DataTable dtSchema = new DataTable();
using (OleDbConnection conn = new OleDbConnection(connectionString))
{
OleDbCommand command = new OleDbCommand(String.Format("SELECT * FROM [{0}A1:II1]", WorksheetName),conn);
OleDbDataAdapter dataAdapter = new OleDbDataAdapter();
dataAdapter.SelectCommand = command;
DataSet dataSet = new DataSet();
dataAdapter.Fill(dataSet);
dtSchema = dataSet.Tables[0];
}

Retrieve Column By Header Name

I am using OLEDB to read the data from an Excel spreadsheet.
var connectionString =
string.Format("Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0}; Extended Properties=Excel 12.0;", fileName);
var adapter = new OleDbDataAdapter("SELECT * FROM [sheet1$]", connectionString);
var ds = new DataSet();
adapter.Fill(ds, "mySheet");
var data = ds.Tables["mySheet"].AsEnumerable();
foreach (var dataRow in data)
{
Console.WriteLine(dataRow[0].ToString());
}
Instead of passing an index to the DataRow to get the value of a column, is there anyway to retrieve the column by the name of the column header?

Try this code:
var connectionString = string.Format("Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0}; Extended Properties=Excel 12.0; HDR=YES", fileName);
var adapter = new OleDbDataAdapter("SELECT * FROM [sheet1$]", connectionString);
var ds = new DataSet();
adapter.Fill(ds, "mySheet");
var data = ds.Tables["mySheet"].AsEnumerable();
foreach (DataRow dataRow in data)
{
Console.WriteLine(dataRow["MyColumnName"].ToString());
Console.WriteLine(dataRow.Field<string>("MyColumnName").ToString());
}
I added in 2 ways to access the data in the row via column Name.
Hope this does the trick!!

Modify your connection string to specify that you have headers in your excel file.
You can do this by setting the HDR value.
Refer this link to for various variations of connection string and build the one that suits your needs"
http://www.connectionstrings.com/excel/

Use a DataTable to have your data.
string strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + **EXCEL FILE PATH** + ";Extended Properties=\"Excel 8.0;HDR=YES;IMEX=1\"";
OleDbConnection conn = new OleDbConnection(strConn);
conn.Open();
OleDbCommand cmd2 = new OleDbCommand("SELECT * FROM [**YOUR SHEET** $]", conn);
cmd2.CommandType = CommandType.Text;
DataTable outputTable2 = new DataTable("myDataTable");
new OleDbDataAdapter(cmd2).Fill(outputTable2);
foreach(Datarow row in outputTable2)
{
String s = row["yourcolumnheader"].ToString();
}

How to read and get data from excel .xlsx

I have excel file with 2 tables. I need to read this tables and get all the values from this tables. But all for what I have is:
OleDbConnection cnn = new OleDbConnection(#"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\MigrateExelSql\Include\TestDb.xlsx; Extended Properties=Excel 12.0;");
OleDbCommand oconn = new OleDbCommand("select * from [Sheet1$]", cnn);
cnn.Open();
OleDbDataAdapter adp = new OleDbDataAdapter(oconn);
DataTable dt = new DataTable();
adp.Fill(dt);
And I don't uderstand what I need to write for get the all values from Username and Email tables. Here is the .xlsx table TestDb Please can somebody help me, because I'm googling the second day and I have no idea for what I must to do.
And when I try to get values by this method it return me an error:
var fileName = string.Format("{0}\\Include\\TestDb.xlsx", Directory.GetCurrentDirectory());
var connectionString = string.Format("Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0}; Extended Properties=Excel 12.0;", fileName);
var adapter = new OleDbDataAdapter("SELECT * FROM [Sheet1$]", connectionString);
var ds = new DataSet();
adapter.Fill(ds, "Username");
var data = ds.Tables["Username"].AsEnumerable();
foreach (var item in data)
{
Console.WriteLine(item);
}
Console.ReadKey();
One more Edit:
string con =
#"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\MigrateExelSql\Include\TestDb.xlsx; Extended Properties=Excel 12.0;";
using(OleDbConnection connection = new OleDbConnection(con))
{
connection.Open();
OleDbCommand command = new OleDbCommand("select * from [Sheet1$]", connection);
using(OleDbDataReader dr = command.ExecuteReader())
{
while(dr.Read())
{
var row1Col0 = dr[0];
Console.WriteLine(row1Col0);
}
}
}
Console.ReadKey();
This will read only first column, but when I try to read dr[1] it will return error: Index was outside bound of the array.

Your xlsx file contains only one sheet and in that sheet there is only one column.
A sheet is treated by the OleDb driver like a datatable and each column in a sheet is considered a datacolumn.
You can't read anything apart one table (Sheet1$) and one column (dr[0]).
If you try to read dr[1] then you are referencing the second column and that column doesn't exist in Sheet1.
Just to test, try to add some values in the second column of the Excel file.
Now you can reference dr[1].

Query excel sheet in c#

I want to read Excel file in c# using following code
string excelFileName = "Book2.xls";
string excelConnectString = #"Provider=Microsoft.Jet.OLEDB.4.0; Data Source=Book2.xls;Extended Properties=""Excel 8.0;HDR=YES;""";
//string excelConnectString = #"Provider = Microsoft.Jet.OLEDB.4.0;Data Source = " + excelFileName + ";" + "Extended Properties = Excel 8.0; HDR=Yes;IMEX=1";
OleDbConnection objConn = new OleDbConnection(excelConnectString);
OleDbCommand objCmd = new OleDbCommand("Select * From [Sheet1$]", objConn);
OleDbDataAdapter objDatAdap = new OleDbDataAdapter();
objDatAdap.SelectCommand = objCmd;
DataSet ds = new DataSet();
objDatAdap.Fill(ds);
Everything is working fine.Now my requirement is to read the excel file something like below
SELECT A,B,D From [Sheet1];

The Select-command should look like this if you want to read A1 to D1:
SELECT * FROM [SHEETNAME_HERE$A1:D1]
Whole Code:
OleDbConnection con = new OleDbConnection(
"provider=Microsoft.Jet.OLEDB.4.0;data source="
+ XLS_FILE_NAME_AND_PATH_HERE
+ ";Extended Properties=Excel 8.0;");
StringBuilder stbQuery = new StringBuilder();
stbQuery.Append("SELECT * FROM [" + SHEETNAME_HERE + "$A1:D1]");
OleDbDataAdapter adp = new OleDbDataAdapter(stbQuery.ToString(), con);
DataSet dsXLS = new DataSet();
adp.Fill(dsXLS);
DataView dvEmp = new DataView(dsXLS.Tables[0]);
dataGridView1.DataSource = dvEmp;

DataTable Contents = new DataTable();
using (OleDbDataAdapter adapter = new OleDbDataAdapter("Select * From [Sheet1$]", objConn))
{
adapter.Fill(Contents);
}
Console.WriteLine(Contents.Rows[0][0]);
You can select a particular cell by passing the proper index.

You can just constuct use query like that:
SELECT FirstName, LastName, Mobile FROM [Sheet1$]
i.e. use first row values as column names.

Read alphanumeric characters from csv file in C#

I am using the following code to read my csv file:
public DataTable ParseCSV(string path)
{
if (!File.Exists(path))
return null;
string full = Path.GetFullPath(path);
string file = Path.GetFileName(full);
string dir = Path.GetDirectoryName(full);
//create the "database" connection string
string connString = "Provider=Microsoft.ACE.OLEDB.12.0;"
+ "Data Source=\"" + dir + "\\\";"
+ "Extended Properties=\"text;HDR=Yes;FMT=Delimited\"";
//create the database query
string query = "SELECT * FROM " + file;
//create a DataTable to hold the query results
DataTable dTable = new DataTable();
//create an OleDbDataAdapter to execute the query
OleDbDataAdapter dAdapter = new OleDbDataAdapter(query, connString);
//fill the DataTable
dAdapter.Fill(dTable);
dAdapter.Dispose();
return dTable;
}
But the above doesn't reads the alphanumeric value from the csv file. it reads only i either numeric or alpha.
Whats the fix i need to make to read the alphanumeric values? Please suggest.

I suggest you use A Fast CSV Reader which does not have this issue and is much more faster.

Remove IMEX=1 from the connection string. I don't think you need it for CSV files.

Try this OleDBAdapter Excel QA I posted via stack overflow.
I have not tried this out, but it sounds interesting! LinqToExcel
they say it can be used on .CSV files as well...

hi all this code is gets alphanumeric values also
using System.Data.OleDb;
string ConnectionString = #"Provider=Microsoft.Jet.OLEDB.4.0;" + "Data Source=" + filepath + ";" + "Extended Properties="+(char)34+"Excel 8.0;IMEX=1;"+(char)34;
string CommandText = "select * from [Sheet1$]";
OleDbConnection myConnection = new OleDbConnection(ConnectionString);
myConnection.Open();
OleDbDataAdapter myAdapter = new OleDbDataAdapter(CommandText, myConnection);
ds = null;
ds = new DataSet();
myAdapter.Fill(ds);