Refactor: move Insert function into db.file

.CHANGELOG.md

@@ -5,3 +5,4 @@
 - [Updater Definition](https://github.com/gotomicro/eql/pull/8)
 - [Metadata API](https://github.com/gotomicro/eql/pull/16)
 - [tagMetaRegistry: default implementation of MetaRegistry](https://github.com/gotomicro/eql/pull/25)
+- [Refactor: move Insert function into db.file](https://github.com/gotomicro/eql/pull/28)

db.go

@@ -23,14 +23,14 @@ type DB struct {
 }
 
 // New returns DB. It's the entry of EQL
-func New(opts...DBOption) *DB {
+func New(opts ...DBOption) *DB {
 	return &DB{
 		metaRegistry: defaultMetaRegistry,
 	}
 }
 
 // Select starts a select query. If columns are empty, all columns will be fetched
-func (*DB) Select(columns...Selectable) *Selector {
+func (*DB) Select(columns ...Selectable) *Selector {
 	panic("implement me")
 }
 
@@ -42,3 +42,8 @@ func (*DB) Delete() *Deleter {
 func (*DB) Update(table interface{}) *Updater {
 	panic("implement me")
 }
+
+// Insert generate Inserter to builder insert query
+func (db *DB) Insert() *Inserter {
+	return &Inserter{}
+}

insert.go

@@ -16,27 +16,21 @@ package eql
 
 // Inserter is used to construct an insert query
 type Inserter struct {
-
 }
 
 func (i *Inserter) Build() (*Query, error) {
 	panic("implement me")
 }
 
-// Insert generate Inserter to builder insert query
-func (db *DB) Insert() *Inserter {
-	return &Inserter{}
-}
-
 // Columns specifies the columns that need to be inserted
 // if cs is empty, all columns will be inserted except auto increment columns
-func (db *DB) Columns(cs...string) *Inserter {
+func (db *DB) Columns(cs ...string) *Inserter {
 	panic("implements me")
 }
 
 // Values specify the rows
 // all the elements must be the same structure
-func (i *Inserter) Values(values...interface{}) *Inserter {
+func (i *Inserter) Values(values ...interface{}) *Inserter {
 	panic("implement me")
 }
 
@@ -51,4 +45,3 @@ func (i *Inserter) OnDuplicateKey() *MysqlUpserter {
 func (i *Inserter) OnConflict(cs ...string) *PgSQLUpserter {
 	panic("implement me")
 }
-