diff --git a/execution/execution.go b/execution/execution.go
index f266457..03693e9 100644
--- a/execution/execution.go
+++ b/execution/execution.go
@@ -628,31 +628,16 @@ var int32Type = reflect.TypeOf(int32(1))
 var uint32Type = reflect.TypeOf(uint32(1))
 var int64Type = reflect.TypeOf(int64(1))
 var uint64Type = reflect.TypeOf(uint64(1))
-var float32Type = reflect.TypeOf(float32(1.1))
-var float64Type = reflect.TypeOf(float64(1.1))
-
-var nullInt8Type = reflect.TypeOf(internal.NullInt8{})
-
-//var nullUInt8Type = reflect.TypeOf(internal.NullUInt8{})
-var nullInt16Type = reflect.TypeOf(internal.NullInt16{})
-
-//var nullUInt16Type = reflect.TypeOf(internal.NullUInt16{})
-var nullInt32Type = reflect.TypeOf(internal.NullInt32{})
-
-//var nullUInt32Type = reflect.TypeOf(internal.NullUInt32{})
-var nullInt64Type = reflect.TypeOf(sql.NullInt64{})
-
-//var nullUInt64Type = reflect.TypeOf(internal.NullUInt64{})
-
-var nullFloat32Type = reflect.TypeOf(internal.NullFloat32{})
-var nullFloat64Type = reflect.TypeOf(sql.NullFloat64{})
-
-var nullStringType = reflect.TypeOf(sql.NullString{})
 
 var nullBoolType = reflect.TypeOf(sql.NullBool{})
-
+var nullInt8Type = reflect.TypeOf(internal.NullInt8{})
+var nullInt16Type = reflect.TypeOf(internal.NullInt16{})
+var nullInt32Type = reflect.TypeOf(internal.NullInt32{})
+var nullInt64Type = reflect.TypeOf(sql.NullInt64{})
+var nullFloat32Type = reflect.TypeOf(internal.NullFloat32{})
+var nullFloat64Type = reflect.TypeOf(sql.NullFloat64{})
+var nullStringType = reflect.TypeOf(sql.NullString{})
 var nullTimeType = reflect.TypeOf(internal.NullTime{})
-
 var nullByteArrayType = reflect.TypeOf(internal.NullByteArray{})
 
 func newScanType(columnType *sql.ColumnType) reflect.Type {
diff --git a/execution/internal/null_types.go b/execution/internal/null_types.go
index 2a64c8a..aae5b11 100644
--- a/execution/internal/null_types.go
+++ b/execution/internal/null_types.go
@@ -128,42 +128,6 @@ func (n NullInt8) Value() (driver.Value, error) {
 
 //===============================================================//
 
-// NullUInt8 struct
-type NullUInt8 struct {
-	Uint8 uint8
-	Valid bool
-}
-
-// Scan implements the Scanner interface.
-func (n *NullUInt8) Scan(value interface{}) error {
-
-	switch v := value.(type) {
-	case uint8:
-		n.Uint8, n.Valid = v, true
-		return nil
-	case []byte:
-		intV, err := strconv.ParseInt(string(v), 10, 8)
-		if err == nil {
-			n.Uint8, n.Valid = uint8(intV), true
-			return nil
-		}
-	}
-
-	n.Valid = false
-
-	return nil
-}
-
-// Value implements the driver Valuer interface.
-func (n NullUInt8) Value() (driver.Value, error) {
-	if !n.Valid {
-		return nil, nil
-	}
-	return n.Uint8, nil
-}
-
-//===============================================================//
-
 // NullInt16 struct
 type NullInt16 struct {
 	Int16 int16
@@ -209,48 +173,6 @@ func (n NullInt16) Value() (driver.Value, error) {
 
 //===============================================================//
 
-// NullUInt16 struct
-type NullUInt16 struct {
-	UInt16 uint16
-	Valid  bool
-}
-
-// Scan implements the Scanner interface.
-func (n *NullUInt16) Scan(value interface{}) error {
-
-	switch v := value.(type) {
-	case uint16:
-		n.UInt16, n.Valid = v, true
-		return nil
-	case int8:
-		n.UInt16, n.Valid = uint16(v), true
-		return nil
-	case uint8:
-		n.UInt16, n.Valid = uint16(v), true
-		return nil
-	case []byte:
-		intV, err := strconv.ParseInt(string(v), 10, 16)
-		if err == nil {
-			n.UInt16, n.Valid = uint16(intV), true
-			return nil
-		}
-	}
-
-	n.Valid = false
-
-	return nil
-}
-
-// Value implements the driver Valuer interface.
-func (n NullUInt16) Value() (driver.Value, error) {
-	if !n.Valid {
-		return nil, nil
-	}
-	return n.UInt16, nil
-}
-
-//===============================================================//
-
 // NullInt32 struct
 type NullInt32 struct {
 	Int32 int32
@@ -302,160 +224,6 @@ func (n NullInt32) Value() (driver.Value, error) {
 
 //===============================================================//
 
-// NullInt32 struct
-type NullUInt32 struct {
-	UInt32 uint32
-	Valid  bool
-}
-
-// Scan implements the Scanner interface.
-func (n *NullUInt32) Scan(value interface{}) error {
-
-	switch v := value.(type) {
-	case uint32:
-		n.UInt32, n.Valid = v, true
-		return nil
-	case int16:
-		n.UInt32, n.Valid = uint32(v), true
-		return nil
-	case uint16:
-		n.UInt32, n.Valid = uint32(v), true
-		return nil
-	case int8:
-		n.UInt32, n.Valid = uint32(v), true
-		return nil
-	case uint8:
-		n.UInt32, n.Valid = uint32(v), true
-		return nil
-	case []byte:
-		intV, err := strconv.ParseInt(string(v), 10, 32)
-		if err == nil {
-			n.UInt32, n.Valid = uint32(intV), true
-			return nil
-		}
-	}
-
-	n.Valid = false
-
-	return nil
-}
-
-// Value implements the driver Valuer interface.
-func (n NullUInt32) Value() (driver.Value, error) {
-	if !n.Valid {
-		return nil, nil
-	}
-	return n.UInt32, nil
-}
-
-//===============================================================//
-
-// NullInt32 struct
-type NullInt64 struct {
-	Int64 int64
-	Valid bool
-}
-
-// Scan implements the Scanner interface.
-func (n *NullInt64) Scan(value interface{}) error {
-	switch v := value.(type) {
-	case int64:
-		n.Int64, n.Valid = v, true
-		return nil
-	case int32:
-		n.Int64, n.Valid = int64(v), true
-		return nil
-	case uint32:
-		n.Int64, n.Valid = int64(v), true
-		return nil
-	case int16:
-		n.Int64, n.Valid = int64(v), true
-		return nil
-	case uint16:
-		n.Int64, n.Valid = int64(v), true
-		return nil
-	case int8:
-		n.Int64, n.Valid = int64(v), true
-		return nil
-	case uint8:
-		n.Int64, n.Valid = int64(v), true
-		return nil
-	case []byte:
-		intV, err := strconv.ParseInt(string(v), 10, 32)
-		if err == nil {
-			n.Int64, n.Valid = int64(intV), true
-			return nil
-		}
-	}
-
-	n.Valid = false
-
-	return nil
-}
-
-// Value implements the driver Valuer interface.
-func (n NullInt64) Value() (driver.Value, error) {
-	if !n.Valid {
-		return nil, nil
-	}
-	return n.Int64, nil
-}
-
-//===============================================================//
-
-// NullInt32 struct
-type NullUInt64 struct {
-	UInt64 uint64
-	Valid  bool
-}
-
-// Scan implements the Scanner interface.
-func (n *NullUInt64) Scan(value interface{}) error {
-	switch v := value.(type) {
-	case uint64:
-		n.UInt64, n.Valid = v, true
-		return nil
-	case int32:
-		n.UInt64, n.Valid = uint64(v), true
-		return nil
-	case uint32:
-		n.UInt64, n.Valid = uint64(v), true
-		return nil
-	case int16:
-		n.UInt64, n.Valid = uint64(v), true
-		return nil
-	case uint16:
-		n.UInt64, n.Valid = uint64(v), true
-		return nil
-	case int8:
-		n.UInt64, n.Valid = uint64(v), true
-		return nil
-	case uint8:
-		n.UInt64, n.Valid = uint64(v), true
-		return nil
-	case []byte:
-		intV, err := strconv.ParseInt(string(v), 10, 32)
-		if err == nil {
-			n.UInt64, n.Valid = uint64(intV), true
-			return nil
-		}
-	}
-
-	n.Valid = false
-
-	return nil
-}
-
-// Value implements the driver Valuer interface.
-func (n NullUInt64) Value() (driver.Value, error) {
-	if !n.Valid {
-		return nil, nil
-	}
-	return n.UInt64, nil
-}
-
-//===============================================================//
-
 // NullFloat32 struct
 type NullFloat32 struct {
 	Float32 float32