<p>How can I retrieve raw time-series data from a Proficy Historian/iHistorian?</p>

<p>Ideally, I would ask for data for a particular tag between two dates.</p>

A coworker of mine put this together:
In web.config:
```
```
<add name="HistorianConnectionString" 
     providerName="ihOLEDB.iHistorian.1" 
     connectionString="
       Provider=ihOLEDB.iHistorian;
       User Id=;
       Password=;
       Data Source=localhost;"
/>
```
```
In the data layer:
```
```
public DataTable GetProficyData(string tagName, DateTime startDate, DateTime endDate)
{
    using (System.Data.OleDb.OleDbConnection cn = new System.Data.OleDb.OleDbConnection())
    {
        cn.ConnectionString = webConfig.ConnectionStrings.ConnectionStrings["HistorianConnectionString"];
        cn.Open();

        string queryString = string.Format(
                "set samplingmode = rawbytime\n select value as theValue,Timestamp from ihrawdata where tagname = '{0}' AND timestamp between '{1}' and '{2}' and value > 0 order by timestamp",
                tagName.Replace("'", "\""), startDate, endDate);

        System.Data.OleDb.OleDbDataAdapter adp = new System.Data.OleDb.OleDbDataAdapter(queryString, cn);
        DataSet ds = new DataSet();

        adp.Fill(ds);
        return ds.Tables[0];
    }
}
```
```
Update:
This worked well but we ran into an issue with tags that don't update very often. If the tag didn't update near the start or end of the requested startDate and endDate, the trends would look bad. Worse, still were cases where there were no explicit points during the window requested--we'd get no data back.
I resolved this by making three queries:
The previous value
before
the start-date
The points between startDate and endDate
The next value
after
the endDate
This is a potentially inefficient way to do it but It Works:
```
```
public DataTable GetProficyData(string tagName, DateTime startDate, DateTime endDate)
{
    DataSet ds = new DataSet();
    string queryString;
    System.Data.OleDb.OleDbDataAdapter adp;

    using (System.Data.OleDb.OleDbConnection cn = new System.Data.OleDb.OleDbConnection())
    {
        cn.ConnectionString = proficyConn.ConnectionString;
        cn.Open();

        // always get a start value
        queryString = string.Format(
             "set samplingmode = lab\nselect value as theValue,Timestamp from ihrawdata where tagname = '{0}' AND timestamp between '{1}' and '{2}' order by timestamp",
            tagName.Replace("'", "\""), startDate.AddMinutes(-1), startDate);
        adp = new System.Data.OleDb.OleDbDataAdapter(queryString, cn);
        adp.Fill(ds);

        // get the range
        queryString = string.Format(
             "set samplingmode = rawbytime\nselect value as theValue,Timestamp from ihrawdata where tagname = '{0}' AND timestamp between '{1}' and '{2}' order by timestamp",
            tagName.Replace("'", "\""), startDate, endDate);
        adp = new System.Data.OleDb.OleDbDataAdapter(queryString, cn);
        adp.Fill(ds);

        // always get an end value
        queryString = string.Format(
             "set samplingmode = lab\nselect value as theValue,Timestamp from ihrawdata where tagname = '{0}' AND timestamp between '{1}' and '{2}' order by timestamp",
        tagName.Replace("'", "\""), endDate.AddMinutes(-1), endDate);
        adp = new System.Data.OleDb.OleDbDataAdapter(queryString, cn);
        adp.Fill(ds);

        return ds.Tables[0];
    }
}
```
```
And yes, I know, those queries should be parameterized.