There is already an open DataReader associated with this Com

Satish

9y2.5kLearn iOS Programming

how to solve There is already an open DataReader associated with this Command which must be closed first.error

9 Replies

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Ramesh Palanivel9y ago
Try this,

using (DbCommand cmd = new CommandBuilder().SetCommandText(string.Format(@"insert into wdccache values ('{0}' ,'{1}', '{2}','{3}')", ID, Exptime, filepath, Key))
.SetCommandType(CommandType.Text)
.ToDbCommand())
{
var reader = cmd.ExecuteReader()
{
while (reader.Read())
{
if (DateTime.Compare(Exptime, DateTime.UtcNow) < 30)
{
wDCTableData = new WDCTableData
{
key = reader.GetValue("Key"),
Exptime = reader.GetValue("ExpirationDate"),
filepath = reader.GetValue("Filepath")
};
}
}
}
}
Satish9y ago
Invalid attempt to read when no data is present.
This error is getting
Satish9y ago
is this correct way read column data
var cmd1 = new .Data.CommandBuilder().SetCommandText(string.Format("select * from wdccache where [Key] = '{0}'", Key)).SetCommandType(CommandType.Text).ToDbCommand();
using (var reader = cmd1.ExecuteReader())
{
if (DateTime.Compare(Exptime, DateTime.UtcNow) < 30)
{
wDCTableData = new WDCTableData
{
key = reader["Key"].ToString(),
Exptime = (DateTime)reader["ExpirationDate"],
filepath = reader["Filepath"].ToString()
};
}
Ramesh Palanivel9y ago
Hi Nageshwar,

Just remove the Using in that "var reader" Method
Gnanavel Sekar9y ago
You need to close your reader connection.
Note that while a DataReader is open, the Connection is in use exclusively by that DataReader. You cannot execute any commands for the Connection, including creating another DataReader, until the original DataReader is closed.

Example:
string queryString =
"SELECT OrderID, CustomerID FROM dbo.Orders;";
using (SqlConnection connection =
new SqlConnection(connectionString))
{
SqlCommand command =
new SqlCommand(queryString, connection);
connection.Open();
SqlDataReader reader = command.ExecuteReader();
// Call Read before accessing data.
while (reader.Read())
{
Console.WriteLine(String.Format("{0}, {1}",
reader[0], reader[1]));
}
// Call Close when done reading.
reader.Close();

Refer More Links for your answer
http://stackoverflow.com/questions/18475195/error-there-is-already-an-open-datareader-associated-with-this-command-which-mu
http://stackoverflow.com/questions/6062192/there-is-already-an-open-datareader-associated-with-this-command-which-must-be-c
https://www.codeproject.com/questions/616154/there-is-already-an-open-datareader-associated-wit
http://stackoverflow.com/questions/6062192/there-is-already-an-open-datareader-associated-with-this-command-which-must-be-c
Satish9y ago
Is this correct

var cmd = new Data.CommandBuilder().SetCommandText(string.Format(@"insert into wdccache values ('{0}' ,'{1}', '{2}','{3}')", ID, Exptime, filepath, Key))
.SetCommandType(CommandType.Text)
.ToDbCommand();
var cmd1 = new Data.CommandBuilder().SetCommandText(string.Format("select * from wdccache"))
.SetCommandType(CommandType.Text)
.ToDbCommand();
using (var reader = cmd1.ExecuteReader())
{

if (DateTime.Compare(Exptime, DateTime.UtcNow) < 30)
{
wDCTableData = new WDCTableData
{
key = reader.GetValue("Key"),
Exptime = reader.GetValue("ExpirationDate"),
filepath = reader.GetValue("Filepath")
};
}
Ramesh Palanivel9y ago
Hi Nageshwar,

The issue is you are trying to execute your command in another using statement, change code like,

DbDataReader reader = cmd.ExecuteReader()
inside first using statement
Satish9y ago
Like this

using (DbCommand cmd = new CommandBuilder().SetCommandText(string.Format(@"insert into wdccache values ('{0}' ,'{1}', '{2}','{3}')", ID, Exptime, filepath, Key))
.SetCommandType(CommandType.Text)
.ToDbCommand())
{
using (DbDataReader reader = cmd.ExecuteReader())
{
while (reader.Read())
{
if (DateTime.Compare(Exptime, DateTime.UtcNow) < 30)
{
wDCTableData = new WDCTableData
{
key = reader.GetValue("Key"),
Exptime = reader.GetValue("ExpirationDate"),
filepath = reader.GetValue("Filepath")
};
}
}
}
}
Ramesh Palanivel9y ago
HI Nageshwar,

Have you opened Datareader with in Datareader, for the reason you are getting this error,

We cannot access the Datareader with in Datareader, try to close the first Data reader or post your solution file, I will help you