Why does jgejala = drkonsultasi.item(0) evaluate to invalid operation?

-2

I have this code:

comkonsultasi = New OleDbCommand("select count(idkonsultasi) from dkonsultasi where idgejala='" & idgejala & "'", conn)

    drkonsultasi = comkonsultasi.ExecuteReader

    jgejala = drkonsultasi.Item(0)

When it runs, I get this exception message on the last line:

InvalidOperationException was unhandled. No data exists for the row/column.

Can anyone can help to resolve this problem?

edited Jan 2 at 15:06

Joel Coehoorn

312k96497733

asked Jan 2 at 14:58

Nobel Rafael

2

Call Read() on the reader.

– GSerg
Jan 2 at 15:02

add a comment |

-2

I have this code:

comkonsultasi = New OleDbCommand("select count(idkonsultasi) from dkonsultasi where idgejala='" & idgejala & "'", conn)

    drkonsultasi = comkonsultasi.ExecuteReader

    jgejala = drkonsultasi.Item(0)

When it runs, I get this exception message on the last line:

InvalidOperationException was unhandled. No data exists for the row/column.

Can anyone can help to resolve this problem?

edited Jan 2 at 15:06

Joel Coehoorn

312k96497733

asked Jan 2 at 14:58

Nobel Rafael

2

Call Read() on the reader.

– GSerg
Jan 2 at 15:02

add a comment |

-2

I have this code:

comkonsultasi = New OleDbCommand("select count(idkonsultasi) from dkonsultasi where idgejala='" & idgejala & "'", conn)

    drkonsultasi = comkonsultasi.ExecuteReader

    jgejala = drkonsultasi.Item(0)

When it runs, I get this exception message on the last line:

InvalidOperationException was unhandled. No data exists for the row/column.

Can anyone can help to resolve this problem?

edited Jan 2 at 15:06

Joel Coehoorn

312k96497733

asked Jan 2 at 14:58

Nobel Rafael

I have this code:

comkonsultasi = New OleDbCommand("select count(idkonsultasi) from dkonsultasi where idgejala='" & idgejala & "'", conn)

    drkonsultasi = comkonsultasi.ExecuteReader

    jgejala = drkonsultasi.Item(0)

When it runs, I get this exception message on the last line:

InvalidOperationException was unhandled. No data exists for the row/column.

Can anyone can help to resolve this problem?

vb.net ado.net oledb

edited Jan 2 at 15:06

Joel Coehoorn

312k96497733

asked Jan 2 at 14:58

Nobel Rafael

edited Jan 2 at 15:06

Joel Coehoorn

312k96497733

asked Jan 2 at 14:58

Nobel Rafael

edited Jan 2 at 15:06

Joel Coehoorn

312k96497733

edited Jan 2 at 15:06

Joel Coehoorn

312k96497733

edited Jan 2 at 15:06

Joel Coehoorn

312k96497733

asked Jan 2 at 14:58

Nobel Rafael

asked Jan 2 at 14:58

Nobel Rafael

asked Jan 2 at 14:58

Nobel Rafael

2

Call Read() on the reader.

– GSerg
Jan 2 at 15:02

add a comment |

2

Call Read() on the reader.

– GSerg
Jan 2 at 15:02

Call Read() on the reader.

– GSerg
Jan 2 at 15:02

add a comment |

1 Answer
1

active

oldest

votes

You have to Read() from the DataReader. It's also very bad to use string concatenation to put data into an SQL query like that. You must use query parameters instead:

Dim sql As String = "select count(idkonsultasi) from dkonsultasi where idgejala= ?"



Using conn As New OleDbConnection("connection string here"), _

      comkonsultasi As New OleDbCommand(sql, conn)

    'Use the actual type and length from the database for this line

    comkonsultasi.Parameters.Add("idgejala", OleDbType.VarWChar, 50).Value = idgejala 

    conn.Open()

    Using drkonsultasi As OleDbDataReader = comkonsultasi.ExecuteReader()

        If drkonsultasi.Read() Then

            jgejala = drkonsultasi.Item(0)

        End Using

    End Using

End Using

edited Jan 2 at 21:36

answered Jan 2 at 15:05

Joel Coehoorn

312k96497733

add a comment |

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1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

You have to Read() from the DataReader. It's also very bad to use string concatenation to put data into an SQL query like that. You must use query parameters instead:

Dim sql As String = "select count(idkonsultasi) from dkonsultasi where idgejala= ?"



Using conn As New OleDbConnection("connection string here"), _

      comkonsultasi As New OleDbCommand(sql, conn)

    'Use the actual type and length from the database for this line

    comkonsultasi.Parameters.Add("idgejala", OleDbType.VarWChar, 50).Value = idgejala 

    conn.Open()

    Using drkonsultasi As OleDbDataReader = comkonsultasi.ExecuteReader()

        If drkonsultasi.Read() Then

            jgejala = drkonsultasi.Item(0)

        End Using

    End Using

End Using

edited Jan 2 at 21:36

answered Jan 2 at 15:05

Joel Coehoorn

312k96497733

add a comment |

You have to Read() from the DataReader. It's also very bad to use string concatenation to put data into an SQL query like that. You must use query parameters instead:

Dim sql As String = "select count(idkonsultasi) from dkonsultasi where idgejala= ?"



Using conn As New OleDbConnection("connection string here"), _

      comkonsultasi As New OleDbCommand(sql, conn)

    'Use the actual type and length from the database for this line

    comkonsultasi.Parameters.Add("idgejala", OleDbType.VarWChar, 50).Value = idgejala 

    conn.Open()

    Using drkonsultasi As OleDbDataReader = comkonsultasi.ExecuteReader()

        If drkonsultasi.Read() Then

            jgejala = drkonsultasi.Item(0)

        End Using

    End Using

End Using

edited Jan 2 at 21:36

answered Jan 2 at 15:05

Joel Coehoorn

312k96497733

add a comment |

You have to Read() from the DataReader. It's also very bad to use string concatenation to put data into an SQL query like that. You must use query parameters instead:

Dim sql As String = "select count(idkonsultasi) from dkonsultasi where idgejala= ?"



Using conn As New OleDbConnection("connection string here"), _

      comkonsultasi As New OleDbCommand(sql, conn)

    'Use the actual type and length from the database for this line

    comkonsultasi.Parameters.Add("idgejala", OleDbType.VarWChar, 50).Value = idgejala 

    conn.Open()

    Using drkonsultasi As OleDbDataReader = comkonsultasi.ExecuteReader()

        If drkonsultasi.Read() Then

            jgejala = drkonsultasi.Item(0)

        End Using

    End Using

End Using

edited Jan 2 at 21:36

answered Jan 2 at 15:05

Joel Coehoorn

312k96497733

You have to Read() from the DataReader. It's also very bad to use string concatenation to put data into an SQL query like that. You must use query parameters instead:

Dim sql As String = "select count(idkonsultasi) from dkonsultasi where idgejala= ?"



Using conn As New OleDbConnection("connection string here"), _

      comkonsultasi As New OleDbCommand(sql, conn)

    'Use the actual type and length from the database for this line

    comkonsultasi.Parameters.Add("idgejala", OleDbType.VarWChar, 50).Value = idgejala 

    conn.Open()

    Using drkonsultasi As OleDbDataReader = comkonsultasi.ExecuteReader()

        If drkonsultasi.Read() Then

            jgejala = drkonsultasi.Item(0)

        End Using

    End Using

End Using

edited Jan 2 at 21:36

answered Jan 2 at 15:05

Joel Coehoorn

312k96497733

edited Jan 2 at 21:36

answered Jan 2 at 15:05

Joel Coehoorn

312k96497733

answered Jan 2 at 15:05

Joel Coehoorn

312k96497733

answered Jan 2 at 15:05

Joel Coehoorn

312k96497733

add a comment |

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