1:  'Server=127.0.0.1;Port=5432;Database=XXXXXXX;User Id=postgres;Password=YYYYYYY;ConnectionLifetime=0;

   2:   

   3:  Public Class Postgres

   4:   

   5:      Dim CN1 As Npgsql.NpgsqlConnection

   6:      Dim CMD1 As Npgsql.NpgsqlCommand

   7:      Dim RDR1 As Npgsql.NpgsqlDataReader

   8:   

   9:      Function Open(ByVal ConnectionString As String) As Npgsql.NpgsqlConnection

  10:          Try

  11:              If CN1 Is Nothing Then

  12:                  CN1 = New Npgsql.NpgsqlConnection(ConnectionString)

  13:                  CN1.Open()

  14:              Else

  15:                  If CN1.FullState = ConnectionState.Open Then

  16:                      'отлично, работаем дальше

  17:                  ElseIf CN1.FullState = ConnectionState.Closed Then

  18:                      CN1.Open()

  19:                  ElseIf CN1.FullState = ConnectionState.Broken Then

  20:                      Throw New Exception("ConnectionState=Broken")

  21:                  ElseIf CN1.FullState = ConnectionState.Connecting Then

  22:                      Throw New Exception("ConnectionState=Connecting")

  23:                  ElseIf CN1.FullState = ConnectionState.Executing Then

  24:                      Throw New Exception("ConnectionState=Executing")

  25:                  ElseIf CN1.FullState = ConnectionState.Fetching Then

  26:                      Throw New Exception("ConnectionState=Fetching")

  27:                  End If

  28:              End If

  29:              Return CN1

  30:          Catch ex As Exception

  31:              MsgBox(ex.Message)

  32:          End Try

  33:      End Function

  34:   

  35:      Function ExecScalar(ByVal CMD As String) As Integer

  36:          If CMD1 Is Nothing Then

  37:              CMD1 = New Npgsql.NpgsqlCommand(CMD, CN1)

  38:          Else

  39:              'команда уже есть - есть ли в ней открытый ридер

  40:              If RDR1 IsNot Nothing Then

  41:                  RDR1.Close()

  42:              End If

  43:              'теперь новая команда

  44:              CMD1.CommandText = CMD

  45:          End If

  46:          RDR1 = CMD1.ExecuteReader

  47:          If RDR1.Read Then

  48:              Return RDR1(0)

  49:          End If

  50:      End Function

  51:   

  52:      Function ExecRDR(ByVal CMD As String) As Npgsql.NpgsqlDataReader

  53:          If CMD1 Is Nothing Then

  54:              CMD1 = New Npgsql.NpgsqlCommand(CMD, CN1)

  55:          Else

  56:              'команда уже есть - есть ли в ней открытый ридер

  57:              If RDR1 IsNot Nothing Then

  58:                  RDR1.Close()

  59:              End If

  60:              'теперь новая команда

  61:              CMD1.CommandText = CMD

  62:          End If

  63:          RDR1 = CMD1.ExecuteReader

  64:          Return RDR1

  65:      End Function

  66:   

  67:      Sub Close()

  68:          If CN1 IsNot Nothing Then

  69:              CN1.Close()

  70:          End If

  71:      End Sub

  72:  End Class