SqlDataReader error, conversion from character

Question

I'm getting an error

Conversion failed when converting from a character string to unique identifier.

and I don't even have any conversion of dates, so I'm pretty lost here.

I am using a parametrized query and adding 2 values that come from a datarowview. In this case if I debug and check the value for the date I get it in this format {8/17/2016 9:08:44 PM}

string query = @"SELECT TOP 1 
                     SensorValue,
                     ActivityDateTime,
                     (Select TimeAlert from Vehicle_config 
                      where VehicleID = '@guid') as TimeAlert,
                     (Select DistanceAlert from Vehicle_config 
                      where VehicleID = '@guid') as DistanceAlert,
                     (Select TimeInterval from Vehicle_config 
                      where VehicleID = '@guid') as TimeInterval,
                     (Select DistanceInterval from Vehicle_config 
                      where VehicleID = '@guid') as DistanceInterval,
                     (Select AlertFlag from Vehicle_config 
                      where VehicleID = '@guid') as AlertFlag, 
                     (Select Litros from Vehicle_config 
                      where VehicleID = '@guid') as Litros
                 FROM 
                     navman_Fuel_activity 
                 WHERE 
                     ActivityDateTime < DATEADD(MI, -5, @date) 
                     AND VehicleId = '@guid' 
                 ORDER BY ActivityDateTime DESC;";

using (SqlConnection sqlConn = new SqlConnection(connectionString))
using (SqlCommand cmd = new SqlCommand(query, sqlConn))
{
    cmd.Parameters.AddWithValue("date", (DateTime)row["ActivityDateTime"]);
    cmd.Parameters.AddWithValue("guid",(Guid)row["VehicleID"]);

    sqlConn.Open();  

    using (var reader = cmd.ExecuteReader())
    {
        if (reader.Read()) // here is where I get the error

your issue is here cmd.Parameters.AddWithValue("guid",(Guid)row["VehicleID"]); — techspider
– techspider, Commented Aug 17, 2016 at 21:19
make sure you have valid Guid in each row for row["VehicleID"] — techspider
– techspider, Commented Aug 17, 2016 at 21:20

B.Rickman · Accepted Answer · 2016-08-17 21:22:59Z

1

I believe the failure is happening on this line

cmd.Parameters.AddWithValue("guid",(Guid)row["VehicleID"]);

i think you need to do this instead of the cast

cmd.Parameters.AddWithValue("guid",new Guid(row["VehicleID"]));

answered Aug 17, 2016 at 21:22

B.Rickman

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