Error while using data reader..

Question

there is already an open datareader associated with this command-error fn1: SQL = query reader = cmd.ExecuteReader() If reader.Read() Then ' operation reader.close() end if reader.close fn:2 SQL = query reader = cmd.ExecuteReader() If reader.Read() Then ' operation reader.close() end if reader.close

Nitin Sontakke · Answer

If this is not resolved please share the code in execComDB method. Looks like something wrong there. In general can you just check if you are creating a new command object every time. Because that's what the error says.

Rajavel G · Answer

Form1 SQL = select Student_image from Student_personal_schooling where Student_rollno=' & lblregno.Text & ' execComDB(SQL) reader = cmd.ExecuteReader() While (reader.Read()) Dim byteBLOBData As [Byte]() = New [Byte](-1) {} byteBLOBData = DirectCast(DirectCast(reader(Student_image) Byte()) [Byte]()) Dim ms As New System.IO.MemoryStream(byteBLOBData) pictureBox1.Image = System.Drawing.Image.FromStream(ms) ' reader.Close() End While reader.Close() Form2: SQL = SELECT Student_curntstdStudent_curntschlStudent_curntcityStudent_curnttalukStudent_curntdistrctStudent_std1Student_schl1Student_city1Student_taluk1Student_district1Student_std2Student_schl2Student_city2Student_taluk2Student_district2Student_std3Student_schl3Student_city3Student_taluk3Student_district3Student_std4Student_schl4Student_city4Student_taluk4Student_distrct4Student_std5Student_schl5Student_city5Student_taluk5Student_distrct5Student_std6Student_schl6Student_city6Student_taluk6Student_district6Student_std7Student_schl7Student_city7Student_taluk7Student_distrct7Student_std8Student_schl8Student_city8Student_taluk8Student_district8Student_std9Student_schl9Student_city9Student_taluk9Student_district9Student_std10Student_schl10Student_city10Student_taluk10Student_district10Student_std11Student_schl11Student_city11Student_talik11Student_district11 FROM Student_school where Student_rollno= ' & Student_update_home.rollno & '  execComDB(SQL) reader = cmd.ExecuteReader() 'cmd.CommandText = SELECT curntstdcurntschlcurntcitycurnttalukcurntdistrctstd1schl1city1taluk1district1std2schl2city2taluk2district2std3schl3city3taluk3district3std4schl4city4taluk4distrct4std5schl5city5taluk5distrct5std6schl6city6taluk6district6std7schl7city7taluk7distrct7std8schl8city8taluk8district8std9schl9city9taluk9district9std10schl10city10taluk10district10std11schl11city11talik11district11 FROM tblschlhistory where rollno=' + no + ' While (reader.Read()) txtcurntstd.Text = reader(Student_curntstd).ToString() End While reader.Close()

Rajavel G · Answer

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

Nitin Sontakke · Answer

First try using using clause if possible so that reader will be closed and discarded. Another thing is why there is reader.Close() write twice? It should be only once. Another thing is the ExecuteReader method has a CommandBehaviour parameter set it to CloseConnection. Let us know if it resolves the issue. Please post the real code and full error.

Rajavel G · Answer

i am using a reade in multiple form so below code is not working.. displaying same eroor..

Manas Mohapatra · Answer

If you want to execute multiple SQL statements then you can use NextResult()  follow below link: http://vb.net-informations.com/ado.net-dataproviders/ado.net-multiple-result-sets.htm OR you can try like below: using (var myConnection = null ) { //myConnection.Open(); var cmd = new MySqlCommand( SELECT * FROM table1  myConnection)) using (var myDataReader = cmd.ExecuteReader()) { while (myDataReader.Read()) { //Perform work. } } // Reader will be Disposed/Closed here cmd.commandText = SELECT * FROM table2 ; using (var reader = cmd.ExecuteReader()) { while (reader.Read()) { //Perform more work } } // Reader will be Disposed/Closed here }