Your are welcome
One note - the proposed code might be (as side effect) accumulating the added rows (in the Rows property of DataTable) in memory (and not just in the database). This might be an issue if it is meant for long-term logging. If this is an issue, I am sure there will be a solution too - such as clearing the old rows from time to time.

I have made an example that logs data into SQL table columnwise (for 4 items), and merges notificatios with the same timestamp into one a single row. It works with following table definition:

USE QuickOPCExamples;
GO

-- The "ColumnarLog" table stores one item per column.
CREATE TABLE ColumnarLog(
[Timestamp] datetime PRIMARY KEY,
Ramp1Value float NULL,
Ramp1Quality int NULL,
Ramp2Value float NULL,
Ramp2Quality int NULL,
Ramp3Value float NULL,
Ramp3Quality int NULL,
Ramp4Value float NULL,
Ramp4Quality int NULL
);
GO


And here is the actual code:

// LogToSqlEnhanced: Logs OPC Data Access item changes into an SQL database, using a subscription. Item values and qualities
// are stored in their respective columns. Notifications with the same timestamp are merged into a single row.

// The database creation script is in the ExamplesNet\MSSQL\QuickOPCExamples.sql file under the product installation
// directory. The example assumes that the database is already created.

using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using OpcLabs.EasyOpc.DataAccess;

namespace LogToSqlEnhanced
{
class Program
{
static void Main()
{
const string connectionString =
"Data Source=(local);Initial Catalog=QuickOPCExamples;Integrated Security=true";

Console.WriteLine("Starting up...");
using (var connection = new SqlConnection(connectionString))
{
connection.Open();

// Create all necessary ADO.NET objects.
var adapter = new SqlDataAdapter("SELECT * FROM ColumnarLog", connection);
var dataSet = new DataSet();
adapter.FillSchema(dataSet, SchemaType.Source, "ColumnarLog");
adapter.InsertCommand = new SqlCommandBuilder(adapter).GetInsertCommand();
adapter.UpdateCommand = new SqlCommandBuilder(adapter).GetUpdateCommand();
DataTable table = dataSet.Tables["ColumnarLog"];

Console.WriteLine("Logging for 30 seconds...");
// Subscribe to an OPC item, using an anonymous method to process the notifications.
int[] handles = EasyDAClient.DefaultInstance.SubscribeMultipleItems(
new[]
{
new DAItemGroupArguments("", "OPCLabs.KitServer.2", "Trends.Ramp (1 s)", 1000, null),
new DAItemGroupArguments("", "OPCLabs.KitServer.2", "Trends.Ramp (10 s)", 1000, null),
new DAItemGroupArguments("", "OPCLabs.KitServer.2", "Trends.Ramp (1 min)", 1000, null),
new DAItemGroupArguments("", "OPCLabs.KitServer.2", "Trends.Ramp (10 min)", 1000, null)
},
(_, eventArgs) =>
{
Console.Write(".");
// In this example, we only log valid data. Production logger would also log errors.
if (eventArgs.Vtq != null)
{
// Fill a DataRow with the OPC data, and add it to a DataTable.
DateTime timestamp =
(eventArgs.Vtq.Timestamp < (DateTime) SqlDateTime.MinValue)
? (DateTime) SqlDateTime.MinValue
: eventArgs.Vtq.Timestamp;

DataRow row = dataSet.Tables["ColumnarLog"].Rows.Find(timestamp);
bool adding = (row == null);
if (adding)
{
row = table.NewRow();
row["Timestamp"] = timestamp;
}

switch (eventArgs.ItemDescriptor.ItemId)
{
case "Trends.Ramp (1 s)":
row["Ramp1Value"] = eventArgs.Vtq.Value ?? DBNull.Value;
row["Ramp1Quality"] = (short)eventArgs.Vtq.Quality;
break;
case "Trends.Ramp (10 s)":
row["Ramp2Value"] = eventArgs.Vtq.Value ?? DBNull.Value;
row["Ramp2Quality"] = (short)eventArgs.Vtq.Quality;
break;
case "Trends.Ramp (1 min)":
row["Ramp3Value"] = eventArgs.Vtq.Value ?? DBNull.Value;
row["Ramp3Quality"] = (short)eventArgs.Vtq.Quality;
break;
case "Trends.Ramp (10 min)":
row["Ramp4Value"] = eventArgs.Vtq.Value ?? DBNull.Value;
row["Ramp4Quality"] = (short)eventArgs.Vtq.Quality;
break;
}

if (adding)
table.Rows.Add(row);

// Update the underlying DataSet using an insert command.
adapter.Update(dataSet, "ColumnarLog");
}
}
);
System.Threading.Thread.Sleep(30 * 1000);
Console.WriteLine();

Console.WriteLine("Shutting down...");
EasyDAClient.DefaultInstance.UnsubscribeMultipleItems(handles);
}

Console.WriteLine("Finished.");
}
}
}


I hope this helps.

I will try to write some example code that does what has been suggested, although it is out of scope of what we do (the goal of the component is to provide the OPC data, but not to do much further with it, because those are the needs that can differ vastly from app to app). Please wait for next post.
It would probably be possible to write some wrapper classes and then use them with Entity Framework, but that seems like an overkill for this kind of task.

Hello,
instead of simply inserting a new row each time a notification is received, you can:

look up if there is an existing row with the same timestamp
if yes, place the newly arrived value into its proper column, leaving other data intact, and update the row
if no, place the newly arrived value into its proper column, set he timestamp, and insert as new row.

Best regards