diff --git a/dialect/dialect.go b/dialect/dialect.go
index 8aa3ae31..5a829735 100644
--- a/dialect/dialect.go
+++ b/dialect/dialect.go
@@ -1,7 +1,7 @@
 package dialect
 
 type Dialect interface {
-	BinVar(i int) string
+	BinVar() string
 	SupportLastInsertId() bool
 	SqlTag(column interface{}, size int) string
 	PrimaryKeyTag(column interface{}, size int) string
diff --git a/dialect/mysql.go b/dialect/mysql.go
index 0e71612b..f9e05170 100644
--- a/dialect/mysql.go
+++ b/dialect/mysql.go
@@ -8,7 +8,7 @@ import (
 
 type mysql struct{}
 
-func (s *mysql) BinVar(i int) string {
+func (s *mysql) BinVar() string {
 	return "?"
 }
 
diff --git a/dialect/postgres.go b/dialect/postgres.go
index 13a0afa0..833a4a09 100644
--- a/dialect/postgres.go
+++ b/dialect/postgres.go
@@ -9,8 +9,8 @@ import (
 type postgres struct {
 }
 
-func (s *postgres) BinVar(i int) string {
-	return fmt.Sprintf("$%v", i)
+func (s *postgres) BinVar() string {
+	return "$%v"
 }
 
 func (s *postgres) SupportLastInsertId() bool {
diff --git a/dialect/sqlite3.go b/dialect/sqlite3.go
index 3dec02ef..84e37c48 100644
--- a/dialect/sqlite3.go
+++ b/dialect/sqlite3.go
@@ -8,7 +8,7 @@ import (
 
 type sqlite3 struct{}
 
-func (s *sqlite3) BinVar(i int) string {
+func (s *sqlite3) BinVar() string {
 	return "?"
 }
 
diff --git a/do.go b/do.go
index 81f0e87f..d70d2c5d 100644
--- a/do.go
+++ b/do.go
@@ -60,7 +60,7 @@ func (s *Do) setModel(value interface{}) *Do {
 
 func (s *Do) addToVars(value interface{}) string {
 	s.sqlVars = append(s.sqlVars, value)
-	return s.chain.d.dialect.BinVar(len(s.sqlVars))
+	return fmt.Sprintf(s.chain.d.dialect.BinVar(), len(s.sqlVars))
 }
 
 func (s *Do) exec(sqls ...string) (err error) {
@@ -209,7 +209,7 @@ func (s *Do) setUpdateAttrs(values interface{}, ignore_protected_attrs ...bool)
 		m := &Model{data: values, do: s}
 		s.updateAttrs = map[string]interface{}{}
 		for _, field := range m.columnsHasValue("other") {
-			s.updateAttrs[field.DbName] = field.Value
+			s.updateAttrs[field.dbName] = field.Value
 		}
 	}
 
@@ -473,7 +473,7 @@ func (s *Do) buildWhereCondition(clause map[string]interface{}) (str string) {
 		m := &Model{data: value, do: s}
 		var sqls []string
 		for _, field := range m.columnsHasValue("other") {
-			sqls = append(sqls, fmt.Sprintf("(%v = %v)", field.DbName, s.addToVars(field.Value)))
+			sqls = append(sqls, fmt.Sprintf("(%v = %v)", field.dbName, s.addToVars(field.Value)))
 		}
 		return strings.Join(sqls, " AND ")
 	}
@@ -532,7 +532,7 @@ func (s *Do) buildNotCondition(clause map[string]interface{}) (str string) {
 		m := &Model{data: value, do: s}
 		var sqls []string
 		for _, field := range m.columnsHasValue("other") {
-			sqls = append(sqls, fmt.Sprintf("(%v <> %v)", field.DbName, s.addToVars(field.Value)))
+			sqls = append(sqls, fmt.Sprintf("(%v <> %v)", field.dbName, s.addToVars(field.Value)))
 		}
 		return strings.Join(sqls, " AND ")
 	}
@@ -641,7 +641,7 @@ func (s *Do) createTable() *Do {
 	var sqls []string
 	for _, field := range s.model.fields("migration") {
 		if len(field.sqlTag()) > 0 {
-			sqls = append(sqls, field.DbName+" "+field.sqlTag())
+			sqls = append(sqls, field.dbName+" "+field.sqlTag())
 		}
 	}
 
@@ -697,12 +697,12 @@ func (s *Do) autoMigrate() *Do {
 		for _, field := range s.model.fields("migration") {
 			var column_name, data_type string
 			sql := fmt.Sprintf("SELECT column_name, data_type FROM information_schema.columns WHERE table_name = %v", s.addToVars(s.tableName()))
-			s.db.QueryRow(fmt.Sprintf(sql+" and column_name = %v", s.addToVars(field.DbName)), s.sqlVars...).Scan(&column_name, &data_type)
+			s.db.QueryRow(fmt.Sprintf(sql+" and column_name = %v", s.addToVars(field.dbName)), s.sqlVars...).Scan(&column_name, &data_type)
 			s.sqlVars = []interface{}{}
 
 			// If column doesn't exist
 			if len(column_name) == 0 && len(field.sqlTag()) > 0 {
-				s.sql = fmt.Sprintf("ALTER TABLE %v ADD %v %v;", s.tableName(), field.DbName, field.sqlTag())
+				s.sql = fmt.Sprintf("ALTER TABLE %v ADD %v %v;", s.tableName(), field.dbName, field.sqlTag())
 				s.exec()
 			}
 		}
@@ -745,7 +745,7 @@ func (s *Do) initializeWithSearchCondition() {
 				case reflect.Struct:
 					m := &Model{data: obj, do: s}
 					for _, field := range m.columnsHasValue("other") {
-						s.model.setValueByColumn(field.DbName, field.Value, s.value)
+						s.model.setValueByColumn(field.dbName, field.Value, s.value)
 					}
 				case reflect.Map:
 					for key, value := range obj.(map[string]interface{}) {
@@ -756,7 +756,7 @@ func (s *Do) initializeWithSearchCondition() {
 		case interface{}:
 			m := &Model{data: value, do: s}
 			for _, field := range m.columnsHasValue("other") {
-				s.model.setValueByColumn(field.DbName, field.Value, s.value)
+				s.model.setValueByColumn(field.dbName, field.Value, s.value)
 			}
 		}
 	}
diff --git a/field.go b/field.go
index 1c5d399c..c30ef665 100644
--- a/field.go
+++ b/field.go
@@ -2,85 +2,68 @@ package gorm
 
 import (
 	"database/sql"
-	"database/sql/driver"
-
-	"time"
-
+	"reflect"
 	"strconv"
 	"strings"
-
-	"reflect"
+	"time"
 )
 
 type Field struct {
 	Name              string
 	Value             interface{}
-	DbName            string
-	AutoCreateTime    bool
-	AutoUpdateTime    bool
-	IsPrimaryKey      bool
-	structField       reflect.StructField
-	modelValue        reflect.Value
+	model             *Model
+	dbName            string
+	isPrimaryKey      bool
+	autoCreateTime    bool
+	autoUpdateTime    bool
+	foreignKey        string
 	beforeAssociation bool
 	afterAssociation  bool
-	foreignKey        string
-	model             *Model
+	reflectValue      reflect.Value
+	structField       reflect.StructField
 }
 
 func (f *Field) isBlank() bool {
-	value := reflect.ValueOf(f.Value)
-	switch value.Kind() {
-	case reflect.Int, reflect.Int64, reflect.Int32:
-		return value.Int() == 0
-	case reflect.String:
-		return value.String() == ""
-	case reflect.Slice:
-		return value.Len() == 0
-	case reflect.Struct:
-		time_value, is_time := f.Value.(time.Time)
-		if is_time {
-			return time_value.IsZero()
-		} else {
-			_, is_scanner := reflect.New(value.Type()).Interface().(sql.Scanner)
-			if is_scanner {
-				return !value.FieldByName("Valid").Interface().(bool)
-			} else {
-				m := &Model{data: value.Interface(), do: f.model.do}
-				fields := m.columnsHasValue("other")
-				if len(fields) == 0 {
-					return true
-				}
-			}
-		}
-	}
-	return false
+	return isBlank(f.reflectValue)
 }
 
-func (f *Field) sqlTag() string {
-	column := getInterfaceValue(f.Value)
-	field_value := reflect.ValueOf(f.Value)
-	switch field_value.Kind() {
+func (f *Field) isScanner() bool {
+	_, is_scanner := reflect.New(f.reflectValue.Type()).Interface().(sql.Scanner)
+	return is_scanner
+}
+
+func (f *Field) isTime() bool {
+	_, is_time := f.Value.(time.Time)
+	return is_time
+}
+
+func (f *Field) sqlTag() (str string) {
+	value := f.Value
+	if f.isScanner() {
+		value = f.reflectValue.Field(0).Interface()
+	}
+	reflect_value := f.reflectValue
+
+	switch reflect_value.Kind() {
 	case reflect.Slice:
-		return ""
+		return
 	case reflect.Struct:
-		_, is_scanner := reflect.New(field_value.Type()).Interface().(sql.Scanner)
-		_, is_time := column.(time.Time)
-		if !is_time && !is_scanner {
-			return ""
+		if !f.isTime() && !f.isScanner() {
+			return
 		}
 	}
 
 	typ, addational_typ, size := parseSqlTag(f.structField.Tag.Get(tagIdentifier))
 
 	if typ == "-" {
-		return ""
+		return
 	}
 
 	if len(typ) == 0 {
-		if f.IsPrimaryKey {
-			typ = f.model.do.chain.d.dialect.PrimaryKeyTag(column, size)
+		if f.isPrimaryKey {
+			typ = f.model.do.chain.d.dialect.PrimaryKeyTag(value, size)
 		} else {
-			typ = f.model.do.chain.d.dialect.SqlTag(column, size)
+			typ = f.model.do.chain.d.dialect.SqlTag(value, size)
 		}
 	}
 
@@ -91,26 +74,23 @@ func (f *Field) sqlTag() string {
 }
 
 func (f *Field) parseAssociation() {
-	field_value := reflect.ValueOf(f.Value)
+	reflect_value := f.reflectValue
 
-	switch field_value.Kind() {
+	switch reflect_value.Kind() {
 	case reflect.Slice:
 		foreign_key := f.model.typeName() + "Id"
-		if reflect.New(field_value.Type().Elem()).Elem().FieldByName(foreign_key).IsValid() {
+		if reflect.New(reflect_value.Type().Elem()).Elem().FieldByName(foreign_key).IsValid() {
 			f.foreignKey = foreign_key
 		}
 		f.afterAssociation = true
 	case reflect.Struct:
-		_, is_time := f.Value.(time.Time)
-		_, is_scanner := reflect.New(field_value.Type()).Interface().(sql.Scanner)
-
-		if !is_scanner && !is_time {
-			if f.modelValue.FieldByName(f.Name + "Id").IsValid() {
+		if !f.isTime() && !f.isScanner() {
+			if f.model.reflectData().FieldByName(f.Name + "Id").IsValid() {
 				f.foreignKey = f.Name + "Id"
 				f.beforeAssociation = true
 			} else {
 				foreign_key := f.model.typeName() + "Id"
-				if reflect.New(field_value.Type()).Elem().FieldByName(foreign_key).IsValid() {
+				if reflect.New(reflect_value.Type()).Elem().FieldByName(foreign_key).IsValid() {
 					f.foreignKey = foreign_key
 				}
 				f.afterAssociation = true
@@ -147,14 +127,3 @@ func parseSqlTag(str string) (typ string, addational_typ string, size int) {
 	}
 	return
 }
-
-func getInterfaceValue(column interface{}) interface{} {
-	if v, ok := column.(reflect.Value); ok {
-		column = v.Interface()
-	}
-
-	if valuer, ok := interface{}(column).(driver.Valuer); ok {
-		column = reflect.New(reflect.ValueOf(valuer).Field(0).Type()).Elem().Interface()
-	}
-	return column
-}
diff --git a/model.go b/model.go
index d4484fcc..da595d71 100644
--- a/model.go
+++ b/model.go
@@ -14,33 +14,22 @@ type Model struct {
 	_cache_fields map[string][]*Field
 }
 
-func (m *Model) primaryKeyZero() bool {
-	return m.primaryKeyValue() <= 0
+func (m *Model) reflectData() reflect.Value {
+	return reflect.Indirect(reflect.ValueOf(m.data))
 }
 
-func (m *Model) primaryKeyValue() int64 {
-	if m.data == nil {
-		return -1
-	}
-	data := reflect.Indirect(reflect.ValueOf(m.data))
+func (m *Model) primaryKeyZero() bool {
+	return isBlank(reflect.ValueOf(m.primaryKeyValue()))
+}
 
-	switch data.Kind() {
-	case reflect.Array, reflect.Chan, reflect.Map, reflect.Ptr, reflect.Slice:
-		return 0
-	default:
-		value := data.FieldByName(m.primaryKey())
-
-		if value.IsValid() {
-			switch value.Kind() {
-			case reflect.Int, reflect.Int64, reflect.Int32:
-				return value.Int()
-			default:
-				return 0
-			}
-		} else {
-			return 0
+func (m *Model) primaryKeyValue() interface{} {
+	if data := m.reflectData(); data.Kind() == reflect.Struct {
+		field := data.FieldByName(m.primaryKey())
+		if data.FieldByName(m.primaryKey()).IsValid() {
+			return field.Interface()
 		}
 	}
+	return 0
 }
 
 func (m *Model) primaryKey() string {
@@ -56,7 +45,7 @@ func (m *Model) fields(operation string) (fields []*Field) {
 		return m._cache_fields[operation]
 	}
 
-	indirect_value := reflect.Indirect(reflect.ValueOf(m.data))
+	indirect_value := m.reflectData()
 	if !indirect_value.IsValid() {
 		return
 	}
@@ -67,30 +56,29 @@ func (m *Model) fields(operation string) (fields []*Field) {
 		if !p.Anonymous && ast.IsExported(p.Name) {
 			var field Field
 			field.Name = p.Name
-			field.DbName = toSnake(p.Name)
-			field.IsPrimaryKey = m.primaryKeyDb() == field.DbName
+			field.dbName = toSnake(p.Name)
+			field.isPrimaryKey = m.primaryKeyDb() == field.dbName
 			value := indirect_value.FieldByName(p.Name)
-			time_value, is_time := value.Interface().(time.Time)
 			field.model = m
-			field.modelValue = indirect_value
 
-			if is_time {
-				field.AutoCreateTime = "created_at" == field.DbName
-				field.AutoUpdateTime = "updated_at" == field.DbName
+			if time_value, is_time := value.Interface().(time.Time); is_time {
+				field.autoCreateTime = "created_at" == field.dbName
+				field.autoUpdateTime = "updated_at" == field.dbName
 
 				switch operation {
 				case "create":
-					if (field.AutoCreateTime || field.AutoUpdateTime) && time_value.IsZero() {
+					if (field.autoCreateTime || field.autoUpdateTime) && time_value.IsZero() {
 						value.Set(reflect.ValueOf(time.Now()))
 					}
 				case "update":
-					if field.AutoUpdateTime {
+					if field.autoUpdateTime {
 						value.Set(reflect.ValueOf(time.Now()))
 					}
 				}
 			}
 
 			field.structField = p
+			field.reflectValue = value
 			field.Value = value.Interface()
 			fields = append(fields, &field)
 		}
@@ -117,17 +105,16 @@ func (m *Model) updatedColumnsAndValues(values map[string]interface{}) (results
 		return values, true
 	}
 
-	data := reflect.Indirect(reflect.ValueOf(m.data))
+	data := m.reflectData()
 	for key, value := range values {
-		field := data.FieldByName(snakeToUpperCamel(key))
-		if field.IsValid() {
+		if field := data.FieldByName(snakeToUpperCamel(key)); field.IsValid() {
 			if field.Interface() != value {
 				switch field.Kind() {
 				case reflect.Int, reflect.Int32, reflect.Int64:
 					if field.Int() != reflect.ValueOf(value).Int() {
 						any_updated = true
+						field.SetInt(reflect.ValueOf(value).Int())
 					}
-					field.SetInt(reflect.ValueOf(value).Int())
 				default:
 					any_updated = true
 					field.Set(reflect.ValueOf(value))
@@ -145,51 +132,46 @@ func (m *Model) updatedColumnsAndValues(values map[string]interface{}) (results
 func (m *Model) columnsAndValues(operation string) map[string]interface{} {
 	results := map[string]interface{}{}
 
-	if m.data != nil {
-		for _, field := range m.fields(operation) {
-			if !field.IsPrimaryKey && (len(field.sqlTag()) > 0) {
-				results[field.DbName] = field.Value
-			}
+	for _, field := range m.fields(operation) {
+		if !field.isPrimaryKey && (len(field.sqlTag()) > 0) {
+			results[field.dbName] = field.Value
 		}
 	}
 	return results
 }
 
 func (m *Model) hasColumn(name string) bool {
-	if m.data == nil {
-		return false
-	}
+	data := m.reflectData()
 
-	data := reflect.Indirect(reflect.ValueOf(m.data))
-	if data.Kind() == reflect.Slice {
-		return reflect.New(data.Type().Elem()).Elem().FieldByName(name).IsValid()
-	} else {
+	if data.Kind() == reflect.Struct {
 		return data.FieldByName(name).IsValid()
+	} else if data.Kind() == reflect.Slice {
+		return reflect.New(data.Type().Elem()).Elem().FieldByName(name).IsValid()
 	}
+	return false
 }
 
 func (m *Model) ColumnAndValue(name string) (has_column bool, is_slice bool, value interface{}) {
-	if m.data != nil {
-		data := reflect.Indirect(reflect.ValueOf(m.data))
-		if data.Kind() == reflect.Slice {
-			has_column = reflect.New(data.Type().Elem()).Elem().FieldByName(name).IsValid()
-			is_slice = true
-		} else {
-			if has_column = data.FieldByName(name).IsValid(); has_column {
-				value = data.FieldByName(name).Interface()
-			}
+	data := m.reflectData()
+
+	if data.Kind() == reflect.Struct {
+		if has_column = data.FieldByName(name).IsValid(); has_column {
+			value = data.FieldByName(name).Interface()
 		}
+	} else if data.Kind() == reflect.Slice {
+		has_column = reflect.New(data.Type().Elem()).Elem().FieldByName(name).IsValid()
+		is_slice = true
 	}
 	return
 }
 
 func (m *Model) typeName() string {
-	typ := reflect.Indirect(reflect.ValueOf(m.data)).Type()
+	typ := m.reflectData().Type()
 	if typ.Kind() == reflect.Slice {
-		typ = typ.Elem()
+		return typ.Elem().Name()
+	} else {
+		return typ.Name()
 	}
-
-	return typ.Name()
 }
 
 func (m *Model) tableName() (str string) {
@@ -198,8 +180,8 @@ func (m *Model) tableName() (str string) {
 		return
 	}
 
-	fm := reflect.Indirect(reflect.ValueOf(m.data)).MethodByName("TableName")
-	if fm.IsValid() {
+	data := m.reflectData()
+	if fm := data.MethodByName("TableName"); fm.IsValid() {
 		if v := fm.Call([]reflect.Value{}); len(v) > 0 {
 			if result, ok := v[0].Interface().(string); ok {
 				return result
@@ -227,8 +209,7 @@ func (m *Model) callMethod(method string) {
 		return
 	}
 
-	fm := reflect.ValueOf(m.data).MethodByName(method)
-	if fm.IsValid() {
+	if fm := reflect.ValueOf(m.data).MethodByName(method); fm.IsValid() {
 		if v := fm.Call([]reflect.Value{}); len(v) > 0 {
 			if verr, ok := v[0].Interface().(error); ok {
 				m.do.err(verr)
@@ -255,7 +236,6 @@ func (m *Model) beforeAssociations() (fields []*Field) {
 
 func (m *Model) afterAssociations() (fields []*Field) {
 	for _, field := range m.fields("null") {
-		field.parseAssociation()
 		if field.afterAssociation && !field.isBlank() {
 			fields = append(fields, field)
 		}
diff --git a/db.go b/sql.go
similarity index 100%
rename from db.go
rename to sql.go
diff --git a/utils.go b/utils.go
index 3ea863d4..ea39a11a 100644
--- a/utils.go
+++ b/utils.go
@@ -3,13 +3,12 @@ package gorm
 import (
 	"bytes"
 	"database/sql"
-
 	"errors"
+	"fmt"
 	"reflect"
 	"strconv"
-
-	"fmt"
 	"strings"
+	"time"
 )
 
 func toSnake(s string) string {
@@ -87,3 +86,31 @@ func setFieldValue(field reflect.Value, value interface{}) bool {
 
 	return false
 }
+
+func isBlank(value reflect.Value) bool {
+	switch value.Kind() {
+	case reflect.Int, reflect.Int64, reflect.Int32:
+		return value.Int() == 0
+	case reflect.String:
+		return value.String() == ""
+	case reflect.Slice:
+		return value.Len() == 0
+	case reflect.Struct:
+		time_value, is_time := value.Interface().(time.Time)
+		if is_time {
+			return time_value.IsZero()
+		} else {
+			_, is_scanner := reflect.New(value.Type()).Interface().(sql.Scanner)
+			if is_scanner {
+				return !value.FieldByName("Valid").Interface().(bool)
+			} else {
+				m := &Model{data: value.Interface()}
+				fields := m.columnsHasValue("other")
+				if len(fields) == 0 {
+					return true
+				}
+			}
+		}
+	}
+	return false
+}