How to manipulate a table from an Access Database with .NET

Question

I have a table named "Streets" in an access db, and I have opened a connection with

OleDbConnection con = OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;" + @"Data source=" + mdbFileName);

How can I get at my table?

Answer 1

Refer this tutorial for basic ado.net C# and access db you would need to create a command and then use a reader to loop through the rows.

Answer 2

If it is needed, here some sample for adding Columns in your DataTable

Answer 3

Add an ADOX COM reference to your project and try out the following code:

using ADOX;

//...
private void Test() {
    string connString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=<path to your .mdb>";
    CatalogClass cat = new CatalogClass();
    cat.let_ActiveConnection(connString);

    RenameField(cat, "YourTableName", "OriginalFieldName", "NewFieldName");
    AddField(cat, "YourTableName", "YourNewFieldName", DataTypeEnum.adVarWChar, 50, "");
}

// Rename a field.
private void RenameField(CatalogClass cat, string tableName, string originalFieldName, string newFieldName) {
    cat.Tables[tableName].Columns[originalFieldName].Name = newFieldName;
}

// Add a field to a specified table.
private void AddField(ADOX.CatalogClass cat, string tableName, string newFieldName, DataTypeEnum varType, int size, string defaultValue) {
    ColumnClass col = new ColumnClass();
    col.Name = newFieldName;
    col.Type = varType;
    col.DefinedSize = size;
    col.Attributes = ColumnAttributesEnum.adColNullable;
    cat.Tables[tableName].Columns.Append((object)col, DataTypeEnum.adInteger, 0);

    if (!string.IsNullOrEmpty(defaultValue)) {
        col.Properties["Default"].Value = defaultValue;
    }

}

Details can be found in the following blog posts:

Rename Field in MS Access Programmatically using ADOX (C#.NET)
Add New Field in MS Access Programmatically using ADOX (C#.Net)

Add data to your new field by using standard ADO.net.

Answer 4

You need to 'ALTER' the table and use the ExecuteNonQuery. Code below:

Dim dbName As String = "<path>\mdbFileName.mdb"
Dim tmpConString As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & dbName & ";Persist Security Info=False"

Dim sqlText As String = ""
Using cn As New OleDbConnection(tmpConString)
  cn.Open()
  sqlText = "ALTER TABLE Table1 ADD COLUMN fldNew TEXT(50)"

  Using cm As New OleDbCommand(sqlText, cn)
    cm.ExecuteNonQuery()
  End Using
End Using

This will add a new column called 'fldNew' to your database. Then you can use a standard UPDATE SQL command to add the data into your new column.