diff --git a/orm/qb_tidb.go b/orm/qb_tidb.go
index 348002e1..c504049e 100644
--- a/orm/qb_tidb.go
+++ b/orm/qb_tidb.go
@@ -20,105 +20,126 @@ import (
 	"strings"
 )
 
+// TiDBQueryBuilder is the SQL build
 type TiDBQueryBuilder struct {
 	Tokens []string
 }
 
+// Select will join the fields
 func (qb *TiDBQueryBuilder) Select(fields ...string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "SELECT", strings.Join(fields, CommaSpace))
 	return qb
 }
 
+// From join the tables
 func (qb *TiDBQueryBuilder) From(tables ...string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "FROM", strings.Join(tables, CommaSpace))
 	return qb
 }
 
+// InnerJoin INNER JOIN the table
 func (qb *TiDBQueryBuilder) InnerJoin(table string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "INNER JOIN", table)
 	return qb
 }
 
+// LeftJoin LEFT JOIN the table
 func (qb *TiDBQueryBuilder) LeftJoin(table string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "LEFT JOIN", table)
 	return qb
 }
 
+// RightJoin RIGHT JOIN the table
 func (qb *TiDBQueryBuilder) RightJoin(table string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "RIGHT JOIN", table)
 	return qb
 }
 
+// On join with on cond
 func (qb *TiDBQueryBuilder) On(cond string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "ON", cond)
 	return qb
 }
 
+// Where join the Where cond
 func (qb *TiDBQueryBuilder) Where(cond string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "WHERE", cond)
 	return qb
 }
 
+// And join the and cond
 func (qb *TiDBQueryBuilder) And(cond string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "AND", cond)
 	return qb
 }
 
+// Or join the or cond
 func (qb *TiDBQueryBuilder) Or(cond string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "OR", cond)
 	return qb
 }
 
+// In join the IN (vals)
 func (qb *TiDBQueryBuilder) In(vals ...string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "IN", "(", strings.Join(vals, CommaSpace), ")")
 	return qb
 }
 
+// OrderBy join the Order by fields
 func (qb *TiDBQueryBuilder) OrderBy(fields ...string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "ORDER BY", strings.Join(fields, CommaSpace))
 	return qb
 }
 
+// Asc join the asc
 func (qb *TiDBQueryBuilder) Asc() QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "ASC")
 	return qb
 }
 
+// Desc join the desc
 func (qb *TiDBQueryBuilder) Desc() QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "DESC")
 	return qb
 }
 
+// Limit join the limit num
 func (qb *TiDBQueryBuilder) Limit(limit int) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "LIMIT", strconv.Itoa(limit))
 	return qb
 }
 
+// Offset join the offset num
 func (qb *TiDBQueryBuilder) Offset(offset int) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "OFFSET", strconv.Itoa(offset))
 	return qb
 }
 
+// GroupBy join the Group by fields
 func (qb *TiDBQueryBuilder) GroupBy(fields ...string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "GROUP BY", strings.Join(fields, CommaSpace))
 	return qb
 }
 
+// Having join the Having cond
 func (qb *TiDBQueryBuilder) Having(cond string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "HAVING", cond)
 	return qb
 }
 
+// Update join the update table
 func (qb *TiDBQueryBuilder) Update(tables ...string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "UPDATE", strings.Join(tables, CommaSpace))
 	return qb
 }
 
+// Set join the set kv
 func (qb *TiDBQueryBuilder) Set(kv ...string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "SET", strings.Join(kv, CommaSpace))
 	return qb
 }
 
+// Delete join the Delete tables
 func (qb *TiDBQueryBuilder) Delete(tables ...string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "DELETE")
 	if len(tables) != 0 {
@@ -127,6 +148,7 @@ func (qb *TiDBQueryBuilder) Delete(tables ...string) QueryBuilder {
 	return qb
 }
 
+// InsertInto join the insert SQL
 func (qb *TiDBQueryBuilder) InsertInto(table string, fields ...string) QueryBuilder {
 	qb.Tokens = append(qb.Tokens, "INSERT INTO", table)
 	if len(fields) != 0 {
@@ -136,16 +158,19 @@ func (qb *TiDBQueryBuilder) InsertInto(table string, fields ...string) QueryBuil
 	return qb
 }
 
+// Values join the Values(vals)
 func (qb *TiDBQueryBuilder) Values(vals ...string) QueryBuilder {
 	valsStr := strings.Join(vals, CommaSpace)
 	qb.Tokens = append(qb.Tokens, "VALUES", "(", valsStr, ")")
 	return qb
 }
 
+// Subquery join the sub as alias
 func (qb *TiDBQueryBuilder) Subquery(sub string, alias string) string {
 	return fmt.Sprintf("(%s) AS %s", sub, alias)
 }
 
+// String join all Tokens
 func (qb *TiDBQueryBuilder) String() string {
 	return strings.Join(qb.Tokens, " ")
 }
diff --git a/session/sess_utils.go b/session/sess_utils.go
index 756f3e4a..d7db5ba8 100644
--- a/session/sess_utils.go
+++ b/session/sess_utils.go
@@ -43,6 +43,7 @@ func init() {
 	gob.Register(map[int]int64{})
 }
 
+// EncodeGob encode the obj to gob
 func EncodeGob(obj map[interface{}]interface{}) ([]byte, error) {
 	for _, v := range obj {
 		gob.Register(v)
@@ -56,6 +57,7 @@ func EncodeGob(obj map[interface{}]interface{}) ([]byte, error) {
 	return buf.Bytes(), nil
 }
 
+// DecodeGob decode data to map
 func DecodeGob(encoded []byte) (map[interface{}]interface{}, error) {
 	buf := bytes.NewBuffer(encoded)
 	dec := gob.NewDecoder(buf)