diff --git a/internal/statements/values.go b/internal/statements/values.go
index b545a605..0ab174d6 100644
--- a/internal/statements/values.go
+++ b/internal/statements/values.go
@@ -44,6 +44,9 @@ func (statement *Statement) Value2Interface(col *schemas.Column, fieldValue refl
 		if col.SQLType.IsBlob() {
 			return data, nil
 		}
+		if nil == data {
+			return nil, nil
+		}
 		return string(data), nil
 	}
 
diff --git a/session_convert.go b/session_convert.go
index a6839947..0707d677 100644
--- a/session_convert.go
+++ b/session_convert.go
@@ -527,3 +527,138 @@ func (session *Session) bytes2Value(col *schemas.Column, fieldValue *reflect.Val
 
 	return nil
 }
+<<<<<<< HEAD
+=======
+
+// convert a field value of a struct to interface for put into db
+func (session *Session) value2Interface(col *core.Column, fieldValue reflect.Value) (interface{}, error) {
+	if fieldValue.CanAddr() {
+		if fieldConvert, ok := fieldValue.Addr().Interface().(core.Conversion); ok {
+			data, err := fieldConvert.ToDB()
+			if err != nil {
+				return 0, err
+			}
+			if col.SQLType.IsBlob() {
+				return data, nil
+			}
+			return string(data), nil
+		}
+	}
+
+	if fieldConvert, ok := fieldValue.Interface().(core.Conversion); ok {
+		data, err := fieldConvert.ToDB()
+		if err != nil {
+			return 0, err
+		}
+		if col.SQLType.IsBlob() {
+			return data, nil
+		}
+		if nil==data {
+			return nil,nil
+		}		
+		return string(data), nil
+	}
+
+	fieldType := fieldValue.Type()
+	k := fieldType.Kind()
+	if k == reflect.Ptr {
+		if fieldValue.IsNil() {
+			return nil, nil
+		} else if !fieldValue.IsValid() {
+			session.engine.logger.Warn("the field[", col.FieldName, "] is invalid")
+			return nil, nil
+		} else {
+			// !nashtsai! deference pointer type to instance type
+			fieldValue = fieldValue.Elem()
+			fieldType = fieldValue.Type()
+			k = fieldType.Kind()
+		}
+	}
+
+	switch k {
+	case reflect.Bool:
+		return fieldValue.Bool(), nil
+	case reflect.String:
+		return fieldValue.String(), nil
+	case reflect.Struct:
+		if fieldType.ConvertibleTo(core.TimeType) {
+			t := fieldValue.Convert(core.TimeType).Interface().(time.Time)
+			tf := session.engine.formatColTime(col, t)
+			return tf, nil
+		}
+
+		if !col.SQLType.IsJson() {
+			// !<winxxp>! 增加支持driver.Valuer接口的结构，如sql.NullString
+			if v, ok := fieldValue.Interface().(driver.Valuer); ok {
+				return v.Value()
+			}
+
+			fieldTable, err := session.engine.autoMapType(fieldValue)
+			if err != nil {
+				return nil, err
+			}
+			if len(fieldTable.PrimaryKeys) == 1 {
+				pkField := reflect.Indirect(fieldValue).FieldByName(fieldTable.PKColumns()[0].FieldName)
+				return pkField.Interface(), nil
+			}
+			return 0, fmt.Errorf("no primary key for col %v", col.Name)
+		}
+
+		if col.SQLType.IsText() {
+			bytes, err := DefaultJSONHandler.Marshal(fieldValue.Interface())
+			if err != nil {
+				session.engine.logger.Error(err)
+				return 0, err
+			}
+			return string(bytes), nil
+		} else if col.SQLType.IsBlob() {
+			bytes, err := DefaultJSONHandler.Marshal(fieldValue.Interface())
+			if err != nil {
+				session.engine.logger.Error(err)
+				return 0, err
+			}
+			return bytes, nil
+		}
+		return nil, fmt.Errorf("Unsupported type %v", fieldValue.Type())
+	case reflect.Complex64, reflect.Complex128:
+		bytes, err := DefaultJSONHandler.Marshal(fieldValue.Interface())
+		if err != nil {
+			session.engine.logger.Error(err)
+			return 0, err
+		}
+		return string(bytes), nil
+	case reflect.Array, reflect.Slice, reflect.Map:
+		if !fieldValue.IsValid() {
+			return fieldValue.Interface(), nil
+		}
+
+		if col.SQLType.IsText() {
+			bytes, err := DefaultJSONHandler.Marshal(fieldValue.Interface())
+			if err != nil {
+				session.engine.logger.Error(err)
+				return 0, err
+			}
+			return string(bytes), nil
+		} else if col.SQLType.IsBlob() {
+			var bytes []byte
+			var err error
+			if (k == reflect.Array || k == reflect.Slice) &&
+				(fieldValue.Type().Elem().Kind() == reflect.Uint8) {
+				bytes = fieldValue.Bytes()
+			} else {
+				bytes, err = DefaultJSONHandler.Marshal(fieldValue.Interface())
+				if err != nil {
+					session.engine.logger.Error(err)
+					return 0, err
+				}
+			}
+			return bytes, nil
+		}
+		return nil, ErrUnSupportedType
+	case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uint:
+		return int64(fieldValue.Uint()), nil
+	default:
+		return fieldValue.Interface(), nil
+	}
+}
+>>>>>>> 解决Conversion接口ToDB() ([]byte, error)方法返回*Type值为nil时,数据类型为[]byte(nil)的bug,解决*Type值为nil时插入数据变为""的bug