ExcelADO.NET v1.0

ExcelADO is a VB class which allows you to open an Excel file via ADO. The class object includes several easy to use methods to read and write data into an excel file. For more advanced features, the class allows you to manipulate the DataSet (DataTable or DataRow) directly. There are 2 different methods of accessing Excel workbooks: OLE and ADO. Click here to see my ExcelOLE class.

This is a VB class which should work in WinForms mode (not tested), but the demo is in ASP.NET.

What is OLE Automation (COM)?
Object Linking and Embedding is a method of controlling an application (Excel) via another application (VB.NET).

Pros:
Allows access to all functions in excel.
Allows you to control everything which Excel can control (data, formatting, menu functions etc)

Cons:
You must have Microsoft Excel installed on your web server - Excel is a very complex file format. Only Microsoft and a hand full of vendors can read it properly - and they all charge $ for their software.
If something goes wrong (Excel decides to ask you a question which is never displayed and can't be answered) the object will sit and wait forever (hang). If you test your script and have a reasonable level of error checking, then this is not an issue.

What is ADO?
Active Data Objects is the normal way of manipulating data in VB.NET. This typically uses a Jet Database driver and a DataSet (DataTable and DataRow) to stream data in and out of the target object.

Pros:
Fast and reliable.
Can use SQL queries to select/update data. (Most methods and properties of the Connection and Recordset objects are supported)

Cons:
You must have Microsoft Excel (or just it's ODBC drivers if you can achieve that) installed on your server - Excel is a very complex file format. Only Microsoft and a hand full of vendors can read it properly - and they all charge $ for their software.
You must have a header row. You can not access any area which does not have a header row (column names) covering it.
Can not delete rows.
Can not create a new file or change it's schema
Supports data only - no formatting etc.

Sample Basic Usage

It is suggested that you copy the class into a separate vb file and compile it into your assemblies, but you can copy the code out and paste it directly into your page if you like.

'Create a new instance
Dim MyExcelFile As New ExcelADO()

'Open a Spreadsheet
If Not MyExcelFile.OpenSpreadsheet(Server.MapPath("ExcelFile.xls")) Then Response.Write(MyExcelFile.ErrorText & "<br>")
'Open a Worksheet (worksheets have a $ after the name)
If Not MyExcelFile.OpenWorksheet("Sheet1$") Then Response.Write(MyExcelFile.ErrorText & "<br>")

'You read rows via ReadRow method
While MyExcelFile.ReadRow
    For intCol = 0 To MyExcelFile.NumColumns -1
        Response.Write(MyExcelFile.ExcelDataRow(intCol) & ", ")
    Next
    Response.Write("<br>")
End While

'or Display each data row via directly accessing the DataTable
For intRow = 0 To MyExcelFile.ExcelDataTable.Rows.Count - 1
    For intCol = 0 To MyExcelFile.ExcelDataTable.Columns.Count - 1
        Response.Write(MyExcelFile.ExcelDataTable.Rows(intRow).Item(intCol) & ", ")
    Next
    Response.Write("<br>")
Next

'Insert a new row
MyExcelFile.NewRow() 'Must create new row first
MyExcelFile.ExcelDataRow(0) = "Newly"
MyExcelFile.ExcelDataRow(1) = "inserted"
MyExcelFile.ExcelDataRow(2) = "row"
'Add the row back to the table (update the table)
If Not MyExcelFile.InsertRow() Then Response.Write(MyExcelFile.ErrorText & "<br>")

MyExcelFile.CloseWorksheet
MyExcelFile.CloseSpreadsheet

See ExcelADODemo.aspx (and ExcelADODemo.aspx.vb) for a full demo.

Properties

ErrorText
String. Show a text message describing the last error.

WorkSheets
String Array. Contains an array of length NumSheets-1 of all the Worksheet and Named space names. This is a 0 based array.

Columns
String Array. Contains an array of length NumColumns-1 of all the Column names (if found). This is a 0 based array.

NumSheets
Integer. Number of tables (Worksheets and Named spaces) in the current Workbook.

NumColumns
Integer. Number of columns in the current worksheet/named space.

SQLStatement
String. Additional SQL query text. Your statement should start with the "WHERE" expression

Driver
DriverType. Defaults to  DriverType.JetExcel
Sets which ODBC driver to use. DriverType.JetText is a delimited text file mode of the Jet driver.

ExcelDataSet
DataSet. The DataSet of the entire Excel spreadsheet.

ExcelDataTable
DataTable. The DataTable from the DataSet of the entire Excel spreadsheet.

ExcelDataRow
DataRow. The current row use by ReadRow, InsertRow and UpdateRow.

ExcelConnection
OLEDBConnector. If you need to alter it directly (generally not used by you).

Methods

OpenSpreadsheet
Returns: True if spreadsheet opened successfully
Parameters: Absolute or Virtual path and file name. Must not be relative (start with "../")
Syntax: OpenSpreadsheet(FileName)
Example: if not OpenSpreadsheet("test.xls") then 'do error handling
Opens the spreadsheet and sets up the ExcelDataSet and ExcelDataTable objects. The driver specified with the Driver variable is used to open the spreadsheet (this defaults to the MS JET4 Excel driver).
Sheets and NumSheets Properties are updated.

OpenWorksheet
Returns: True if the Worksheet opened successfully
Parameters: Worksheet name
Syntax: OpenWorksheet(TabName)
Example: if not OpenWorksheet("Sheet1$") then 'do error handling
Activates the selected Worksheet - OpenSpreadsheet must be run before this. All other methods in this class require this to be run before them (ie ReadRow).
NOTE: You can not create a new file in this class to write to - you must use an existing file as your template.

SQLExecute
Returns: Number of records affected
Parameters: SQL command string
Syntax: SQLExecute(strSQL)
Example: if SQLExecute("Sheet1$") < 1 then 'do error handling
Executes SQL command on the file. Used internally, but may be of value to you too.

ReadRow
Returns: True if the current row is valid (1 to 65536) and the recordset is no EOF.
Parameters: none
Syntax: ReadRow
Example: if not ReadRow() then 'do error handling
Reads the current row of the DataSet into the ExcelDataRow object.

NewRow
Returns: nothing
Parameters: none
Syntax: NewRow
Example: NewRow()
Creates a new ExcelDataRow object ready to be altered.

InsertRow
Returns: True if inserted correctly
Parameters: none
Syntax: InsertRow()
Example: if not InsertRow() then 'do error handling
Added the ExcelDataRow object back into the DataSet and issues a SQL command to insert it to the file.
NewRow() must be called before altering the ExcelDataRow object.

UpdateRow
Returns: True if updated correctly
Parameters: none
Syntax: UpdateRow()
Example: if not UpdateRow() then 'do error handling
The changed ExcelDataRow values are sent via a SQL command to be updated in the file.
Altering the ExcelDataRow object will automatically update the DataSet (linked), but this method must be called to commit to the file.
NOTE: More the one row which has the same values, will update all rows which are the same.

ColumnData
Returns: The data located on the currently read row and the selected column
Parameters: Column number (from 1 to 256)
Syntax: ColumnData(Column)
Example: mycell = ColumnData(2)
Retrieves the data from the result of the ReadRow method.

CloseWorksheet
Returns: none
Parameters: none
Syntax: CloseWorksheet
Example: CloseWorksheet
Clears the DataSet.

CloseSpreadsheet
Returns: none
Parameters: none
Syntax: CloseSpreadsheet
Example: CloseSpreadsheet
Closes the spreadsheet, releasing file locks and resources.

Run ExcelADODemo.aspx for a full demo and reference code.
If you improve this code (this is version 1 so plenty to improve upon), please send me a copy! Thanks!

Hunter Beanland
hunter @ beanland.net.au
http://www.beanland.net.au/programming/dotnet/

Version History
1.02 Fixed SQL in Update function. Slight refactor.
1.0 First version based on my ExcelADO v1.0 class (classic ASP).