diff --git a/Vp.FSharp.Sql.Tests/Mocks.fs b/Vp.FSharp.Sql.Tests/Mocks.fs
index d04467a..b5c7add 100644
--- a/Vp.FSharp.Sql.Tests/Mocks.fs
+++ b/Vp.FSharp.Sql.Tests/Mocks.fs
@@ -17,7 +17,7 @@ type DbField' =
 
 type Data =
     { Columns: DbField' list list
-      GetValues: int32 -> int32 -> Object list
+      GetValues: int32 -> int32 -> obj list
       CountRows: int32 -> int32
       CountResultSets: int32 }
 
@@ -25,6 +25,52 @@ type Response =
     | Reader of (CommandBehavior -> DbDataReader)
     | NonQuery of int32
 
+type IIsDisposed =
+    inherit IDisposable
+    abstract member IsDisposed : bool with get
+
+[<AbstractClass>]
+type IsDisposedDbConnection() =
+
+    inherit DbConnection()
+    let mutable isDisposed = false
+    interface IIsDisposed with member this.IsDisposed = isDisposed
+    member this.CheckDisposed(value) =
+        if isDisposed then raise (ObjectDisposedException("Connection already disposed"))
+        else value
+    override this.Dispose(disposing) =
+        this.CheckDisposed()
+        base.Dispose(disposing)
+        isDisposed <- true
+
+[<AbstractClass>]
+type IsDisposedDbCommand() =
+    inherit DbCommand()
+
+    let mutable isDisposed = false
+    interface IIsDisposed with member this.IsDisposed = isDisposed
+    member this.CheckDisposed(value) =
+        if isDisposed then raise (ObjectDisposedException("Command already disposed"))
+        else value
+    override this.Dispose(disposing) =
+        this.CheckDisposed()
+        base.Dispose(disposing)
+        isDisposed <- true
+
+[<AbstractClass>]
+type IsDisposedDbDataReader() =
+    inherit DbDataReader()
+
+    let mutable isDisposed = false
+    interface IIsDisposed with member this.IsDisposed = isDisposed
+    member this.CheckDisposed(value) =
+        if isDisposed then raise (ObjectDisposedException("Data Reader already disposed"))
+        else value
+    override this.Dispose(disposing) =
+        this.CheckDisposed()
+        base.Dispose(disposing)
+        isDisposed <- true
+
 let fakeData values columns =
     { Columns = columns
       GetValues =
@@ -60,137 +106,155 @@ let makeConf logger =
 let makeReader data _ =
     let mutable currentRowIndex = -1
     let mutable currentResultSetIndex = 0
-    { new DbDataReader()
+    { new IsDisposedDbDataReader()
         with
-        member this.Depth with get() = 0
-        member this.FieldCount with get() =
+        member this.Depth with get () = this.CheckDisposed(0)
+        member this.FieldCount with get () =
             List.length data.Columns.[currentResultSetIndex]
-        member this.HasRows with get() =
+            |> this.CheckDisposed
+        member this.HasRows with get () =
             data.CountRows currentResultSetIndex > 0
-        member this.IsClosed with get() = true
-        member this.RecordsAffected with get() = 0
-        member this.Item
-            with get(ordinal: int32):Object = null
-        member this.Item
-            with get(name: string):Object = null
+            |> this.CheckDisposed
+        member this.IsClosed with get () = this.CheckDisposed(true)
+        member this.RecordsAffected with get () = this.CheckDisposed(0)
+        member this.Item with get (ordinal: int32): obj = this.CheckDisposed(null)
+        member this.Item with get (name: string): obj = this.CheckDisposed(null)
         member this.GetDataTypeName (ordinal: int32) =
             data.Columns.[currentResultSetIndex].[ordinal].NativeTypeName
-        member this.GetEnumerator () = null
+            |> this.CheckDisposed
+        member this.GetEnumerator () = this.CheckDisposed(null)
         member this.GetFieldType (ordinal: int32) =
             data.Columns.[currentResultSetIndex].[ordinal].FieldType
+            |> this.CheckDisposed
         member this.GetName (ordinal: int32) =
             data.Columns.[currentResultSetIndex].[ordinal].Name
-        member this.GetOrdinal (name: string) = 0
-        member this.GetBoolean (ordinal: int32) = true
-        member this.GetByte (ordinal: int32) = 0uy
-        member this.GetBytes (ordinal, dataOffset, buffer, bufferOffset, length) = 0L
-        member this.GetChar (ordinal: int32) = 'a'
-        member this.GetChars (ordinal, dataOffset, buffer, bufferOffset, length) = 0L
-        member this.GetDateTime (ordinal: int32) = DateTime.Today
-        member this.GetDecimal (ordinal: int32) = 0M
-        member this.GetDouble (ordinal: int32) = 0.0
-        member this.GetFloat (ordinal: int32) = 0F
-        member this.GetGuid (ordinal: int32) = Guid.Empty
-        member this.GetInt16 (ordinal: int32) = 0s
-        member this.GetInt32 (ordinal: int32) = 0
-        member this.GetInt64 (ordinal: int32) = 0L
-        member this.GetString (ordinal: int32) = ""
+            |> this.CheckDisposed
+        member this.GetOrdinal (name: string) = this.CheckDisposed(0)
+        member this.GetBoolean (ordinal: int32) = this.CheckDisposed(true)
+        member this.GetByte (ordinal: int32) = this.CheckDisposed(0uy)
+        member this.GetBytes (ordinal, dataOffset, buffer, bufferOffset, length) = this.CheckDisposed(0L)
+        member this.GetChar (ordinal: int32) = this.CheckDisposed('a')
+        member this.GetChars (ordinal, dataOffset, buffer, bufferOffset, length) = this.CheckDisposed(0L)
+        member this.GetDateTime (ordinal: int32) = this.CheckDisposed(DateTime.Today)
+        member this.GetDecimal (ordinal: int32) = this.CheckDisposed(0M)
+        member this.GetDouble (ordinal: int32) = this.CheckDisposed(0.0)
+        member this.GetFloat (ordinal: int32) = this.CheckDisposed(0F)
+        member this.GetGuid (ordinal: int32) = this.CheckDisposed(Guid.Empty)
+        member this.GetInt16 (ordinal: int32) = this.CheckDisposed(0s)
+        member this.GetInt32 (ordinal: int32) = this.CheckDisposed(0)
+        member this.GetInt64 (ordinal: int32) = this.CheckDisposed(0L)
+        member this.GetString (ordinal: int32) = this.CheckDisposed("")
         member this.GetValue (ordinal: int32) =
             (data.GetValues currentResultSetIndex currentRowIndex).[ordinal]
-        member this.GetValues values = 0
+            |> this.CheckDisposed
+        member this.GetValues values = this.CheckDisposed(0)
         member this.IsDBNull (ordinal: int32) =
             (data.GetValues currentResultSetIndex currentRowIndex).[ordinal] = null
+            |> this.CheckDisposed
         member this.NextResult () =
             currentResultSetIndex <- currentResultSetIndex + 1
             currentRowIndex <- -1
             currentResultSetIndex < data.CountResultSets
+            |> this.CheckDisposed
         member this.Read () =
             currentRowIndex <- currentRowIndex + 1
             currentRowIndex < data.CountRows currentResultSetIndex
-    }
+            |> this.CheckDisposed
+    } :> DbDataReader
 
 let makeCommand connection response =
     let mutable connection = connection
     let mutable cmdTxt = ""
-    { new DbCommand()
+    { new IsDisposedDbCommand()
         with
         member this.CommandText
-            with get() = cmdTxt
-            and set v = cmdTxt <- v
+            with get () = this.CheckDisposed(cmdTxt)
+            and  set v  = this.CheckDisposed(cmdTxt <- v)
         member this.CommandTimeout
-            with get() = 0
-            and set v = ()
+            with get () = this.CheckDisposed(0)
+            and  set v  = this.CheckDisposed()
         member this.CommandType
-            with get() = CommandType.Text
-            and set v = ()
+            with get () = this.CheckDisposed(CommandType.Text)
+            and  set v = ()
         member this.DbConnection
-            with get() = connection
-            and set v = connection <- v
+            with get () = this.CheckDisposed(connection)
+            and  set v  = this.CheckDisposed(connection <- v)
         member this.DbParameterCollection
-            with get() = null
+            with get() = this.CheckDisposed(null)
         member this.DbTransaction
-            with get() = null
-            and set v = ()
+            with get () = this.CheckDisposed(null)
+            and  set v  = this.CheckDisposed()
         member this.DesignTimeVisible
-            with get() = false
-            and set v = ()
+            with get () = this.CheckDisposed(false)
+            and  set v  = this.CheckDisposed()
         member this.UpdatedRowSource
-            with get() = UpdateRowSource()
-            and set v = ()
-        member this.Cancel () = ()
-        member this.CreateDbParameter () = null
+            with get () = this.CheckDisposed(UpdateRowSource())
+            and  set v  = this.CheckDisposed()
+        member this.Cancel () = this.CheckDisposed()
+        member this.CreateDbParameter () = this.CheckDisposed(null)
         member this.ExecuteDbDataReader commandBehavior =
             match response with
             | Reader callBackReader -> callBackReader commandBehavior
             | _ -> failwith "ExecuteDbDataReader"
+            |> this.CheckDisposed
         member this.ExecuteNonQuery () =
             match response with
             | NonQuery response -> response
             | _ -> failwith "ExecuteNonQuery"
-        member this.ExecuteScalar () = null
-        member this.Prepare () = ()
-    }
+            |> this.CheckDisposed
+        member this.ExecuteScalar () = this.CheckDisposed(null)
+        member this.Prepare () = this.CheckDisposed()
+    } :> DbCommand
 
 let makeConnectionReader cs state openCallback closeCallback response =
     let mutable connectionString = cs
-    { new DbConnection()
+    { new IsDisposedDbConnection()
         with
         member this.ConnectionString
-            with get() = connectionString
-            and set v = connectionString <- v
-        member this.Database
-            with get() = ""
-        member this.DataSource
-            with get() = ""
-        member this.ServerVersion
-            with get() = ""
-        member this.State
-            with get() = state
-        member this.Close () = closeCallback ()
-        member this.ChangeDatabase dbName = ()
-        member this.Open() = openCallback ()
-        member this.BeginDbTransaction isolationLevel = failwith "BeginDbTransaction not called"
-        member this.CreateDbCommand () = makeCommand this response
-    }
+            with get () = this.CheckDisposed(connectionString)
+            and  set v  = this.CheckDisposed(connectionString <- v)
+        member this.Database with get () = this.CheckDisposed("")
+        member this.DataSource with get () = this.CheckDisposed("")
+        member this.ServerVersion with get () = this.CheckDisposed("")
+        member this.State with get () = this.CheckDisposed(state)
+        member this.Close () =
+            closeCallback ()
+            |> this.CheckDisposed
+        member this.ChangeDatabase dbName = this.CheckDisposed()
+        member this.Open() =
+            openCallback ()
+            |> this.CheckDisposed
+        member this.BeginDbTransaction isolationLevel =
+            failwith "BeginDbTransaction not called"
+            |> this.CheckDisposed
+
+        member this.CreateDbCommand () =
+            makeCommand this response
+            |> this.CheckDisposed
+    } :> DbConnection
 
 let makeConnection cs state openCallback closeCallback response =
     let mutable connectionString = cs
-    { new DbConnection()
+    { new IsDisposedDbConnection()
         with
         member this.ConnectionString
-            with get() = connectionString
-            and set v = connectionString <- v
-        member this.Database
-            with get() = ""
-        member this.DataSource
-            with get() = ""
-        member this.ServerVersion
-            with get() = ""
-        member this.State
-            with get() = state
-        member this.Close () = closeCallback ()
-        member this.ChangeDatabase dbName = ()
-        member this.Open() = openCallback ()
-        member this.BeginDbTransaction isolationLevel = failwith "BeginDbTransaction not called"
-        member this.CreateDbCommand () = makeCommand this response
-    }
+            with get () = this.CheckDisposed(connectionString)
+            and  set v  = this.CheckDisposed(connectionString <- v)
+        member this.Database with get () = this.CheckDisposed("")
+        member this.DataSource with get () = this.CheckDisposed("")
+        member this.ServerVersion with get () = this.CheckDisposed("")
+        member this.State with get () = this.CheckDisposed(state)
+        member this.Close () =
+            closeCallback ()
+            |> this.CheckDisposed
+        member this.ChangeDatabase dbName = this.CheckDisposed()
+        member this.Open() =
+            openCallback ()
+            |> this.CheckDisposed
+        member this.BeginDbTransaction isolationLevel =
+            failwith "BeginDbTransaction not called"
+            |> this.CheckDisposed
+        member this.CreateDbCommand () =
+            makeCommand this response
+            |> this.CheckDisposed
+    } :> DbConnection
diff --git a/Vp.FSharp.Sql.Tests/SqlCommand for querySeqSync should.fs b/Vp.FSharp.Sql.Tests/SqlCommand for querySeqSync should.fs
index ebaa210..280f2f8 100644
--- a/Vp.FSharp.Sql.Tests/SqlCommand for querySeqSync should.fs	
+++ b/Vp.FSharp.Sql.Tests/SqlCommand for querySeqSync should.fs	
@@ -14,11 +14,9 @@ open Vp.FSharp.Sql
 open Vp.FSharp.Sql.Tests.Helpers
 
 
-let toFieldName =
-    sprintf "id%i"
+let toFieldName = sprintf "id%i"
+let toFieldNames = List.map toFieldName
 
-let toFieldNames =
-    List.map toFieldName
 
 let readValueByFieldName (columns: string list) _ _ (reader: SqlRecordReader<DbDataReader>) =
     columns
@@ -276,7 +274,7 @@ let ``log for just command events on globalLogger if connection initially not cl
     let data = Mocks.fakeData
                 [[
                         [1;null;3]
-                        [4;5;6]
+                        [4;5   ;6]
                 ]]
                 [[
                     { Name = "id0"
diff --git a/Vp.FSharp.Sql/SqlCommand.fs b/Vp.FSharp.Sql/SqlCommand.fs
index 4de2e9a..334dcb7 100644
--- a/Vp.FSharp.Sql/SqlCommand.fs
+++ b/Vp.FSharp.Sql/SqlCommand.fs
@@ -212,36 +212,38 @@ module Vp.FSharp.Sql.SqlCommand
     /// This function runs synchronously.
     let querySeqSync (connection: #DbConnection) deps conf
         (read: Read<_, _>) commandDefinition =
-        let wasClosed = connection.State = ConnectionState.Closed
-        let log sqlLog = log4 conf commandDefinition sqlLog
-        let connectionStopwatch = Stopwatch()
-        let commandStopwatch = Stopwatch()
-        use command = setupCommandSync deps commandDefinition connection
+        seq {
+            let wasClosed = connection.State = ConnectionState.Closed
+            let log sqlLog = log4 conf commandDefinition sqlLog
+            let connectionStopwatch = Stopwatch()
+            let commandStopwatch = Stopwatch()
+            use command = setupCommandSync deps commandDefinition connection
 
-        try
-            if wasClosed then
-                setupConnectionSync connection
-                connectionStopwatch.Start()
-                ConnectionOpened connection |> log
+            try
+                if wasClosed then
+                    setupConnectionSync connection
+                    connectionStopwatch.Start()
+                    ConnectionOpened connection |> log
 
-            CommandPrepared command |> log
-            commandStopwatch.Start ()
-            use dbDataReader = deps.ExecuteReader command
-            let items =
-                Seq.initInfinite(fun _ -> dbDataReader)
-                |> SkipFirstSeq.scan(readNextRecordSync) { Continue = true; SetIndex = 0; RecordIndex = -1 }
-                |> Seq.takeWhile(fun state -> state.Continue)
-                |> Seq.mapChange(fun state -> state.SetIndex) (fun _ -> SqlRecordReader(dbDataReader))
-                |> Seq.map(fun (state, rowReader) -> read state.SetIndex state.RecordIndex rowReader )
-            items
+                CommandPrepared command |> log
+                commandStopwatch.Start ()
+                use dbDataReader = deps.ExecuteReader command
+                let items =
+                    Seq.initInfinite(fun _ -> dbDataReader)
+                    |> SkipFirstSeq.scan(readNextRecordSync) { Continue = true; SetIndex = 0; RecordIndex = -1 }
+                    |> Seq.takeWhile(fun state -> state.Continue)
+                    |> Seq.mapChange(fun state -> state.SetIndex) (fun _ -> SqlRecordReader(dbDataReader))
+                    |> Seq.map(fun (state, rowReader) -> read state.SetIndex state.RecordIndex rowReader )
+                yield! items
 
-        finally
-            commandStopwatch.Stop ()
-            CommandExecuted (command, commandStopwatch.Elapsed) |> log
-            if wasClosed then
-                connection.Close()
-                connectionStopwatch.Stop ()
-                ConnectionClosed (connection, connectionStopwatch.Elapsed) |> log
+            finally
+                commandStopwatch.Stop ()
+                CommandExecuted (command, commandStopwatch.Elapsed) |> log
+                if wasClosed then
+                    connection.Close()
+                    connectionStopwatch.Stop ()
+                    ConnectionClosed (connection, connectionStopwatch.Elapsed) |> log
+        }
 
     /// Execute the command and return the sets of rows as a list accordingly to the command definition.
     /// This function runs asynchronously.