diff --git a/core/db.go b/core/db.go
index 50c64c6f..ef5ab227 100644
--- a/core/db.go
+++ b/core/db.go
@@ -23,6 +23,7 @@ var (
 	DefaultCacheSize = 200
 )
 
+// MapToSlice map query and struct as sql and args
 func MapToSlice(query string, mp interface{}) (string, []interface{}, error) {
 	vv := reflect.ValueOf(mp)
 	if vv.Kind() != reflect.Ptr || vv.Elem().Kind() != reflect.Map {
@@ -44,6 +45,7 @@ func MapToSlice(query string, mp interface{}) (string, []interface{}, error) {
 	return query, args, err
 }
 
+// StructToSlice converts a query and struct as sql and args
 func StructToSlice(query string, st interface{}) (string, []interface{}, error) {
 	vv := reflect.ValueOf(st)
 	if vv.Kind() != reflect.Ptr || vv.Elem().Kind() != reflect.Struct {
@@ -176,6 +178,7 @@ func (db *DB) QueryMap(query string, mp interface{}) (*Rows, error) {
 	return db.QueryMapContext(context.Background(), query, mp)
 }
 
+// QueryStructContext query rows with struct
 func (db *DB) QueryStructContext(ctx context.Context, query string, st interface{}) (*Rows, error) {
 	query, args, err := StructToSlice(query, st)
 	if err != nil {
@@ -184,10 +187,12 @@ func (db *DB) QueryStructContext(ctx context.Context, query string, st interface
 	return db.QueryContext(ctx, query, args...)
 }
 
+// QueryStruct query rows with struct
 func (db *DB) QueryStruct(query string, st interface{}) (*Rows, error) {
 	return db.QueryStructContext(context.Background(), query, st)
 }
 
+// QueryRowContext query row with args
 func (db *DB) QueryRowContext(ctx context.Context, query string, args ...interface{}) *Row {
 	rows, err := db.QueryContext(ctx, query, args...)
 	if err != nil {
@@ -196,10 +201,12 @@ func (db *DB) QueryRowContext(ctx context.Context, query string, args ...interfa
 	return &Row{rows, nil}
 }
 
+// QueryRow query row with args
 func (db *DB) QueryRow(query string, args ...interface{}) *Row {
 	return db.QueryRowContext(context.Background(), query, args...)
 }
 
+// QueryRowMapContext query row with map
 func (db *DB) QueryRowMapContext(ctx context.Context, query string, mp interface{}) *Row {
 	query, args, err := MapToSlice(query, mp)
 	if err != nil {
@@ -208,10 +215,12 @@ func (db *DB) QueryRowMapContext(ctx context.Context, query string, mp interface
 	return db.QueryRowContext(ctx, query, args...)
 }
 
+// QueryRowMap query row with map
 func (db *DB) QueryRowMap(query string, mp interface{}) *Row {
 	return db.QueryRowMapContext(context.Background(), query, mp)
 }
 
+// QueryRowStructContext query row with struct
 func (db *DB) QueryRowStructContext(ctx context.Context, query string, st interface{}) *Row {
 	query, args, err := StructToSlice(query, st)
 	if err != nil {
@@ -220,6 +229,7 @@ func (db *DB) QueryRowStructContext(ctx context.Context, query string, st interf
 	return db.QueryRowContext(ctx, query, args...)
 }
 
+// QueryRowStruct query row with struct
 func (db *DB) QueryRowStruct(query string, st interface{}) *Row {
 	return db.QueryRowStructContext(context.Background(), query, st)
 }
@@ -239,10 +249,12 @@ func (db *DB) ExecMapContext(ctx context.Context, query string, mp interface{})
 	return db.ExecContext(ctx, query, args...)
 }
 
+// ExecMap exec query with map
 func (db *DB) ExecMap(query string, mp interface{}) (sql.Result, error) {
 	return db.ExecMapContext(context.Background(), query, mp)
 }
 
+// ExecStructContext exec query with map
 func (db *DB) ExecStructContext(ctx context.Context, query string, st interface{}) (sql.Result, error) {
 	query, args, err := StructToSlice(query, st)
 	if err != nil {
@@ -251,6 +263,7 @@ func (db *DB) ExecStructContext(ctx context.Context, query string, st interface{
 	return db.ExecContext(ctx, query, args...)
 }
 
+// ExecContext exec query with args
 func (db *DB) ExecContext(ctx context.Context, query string, args ...interface{}) (sql.Result, error) {
 	hookCtx := contexts.NewContextHook(ctx, query, args)
 	ctx, err := db.beforeProcess(hookCtx)
@@ -265,6 +278,7 @@ func (db *DB) ExecContext(ctx context.Context, query string, args ...interface{}
 	return res, nil
 }
 
+// ExecStruct exec query with struct
 func (db *DB) ExecStruct(query string, st interface{}) (sql.Result, error) {
 	return db.ExecStructContext(context.Background(), query, st)
 }
@@ -288,6 +302,7 @@ func (db *DB) afterProcess(c *contexts.ContextHook) error {
 	return err
 }
 
+// AddHook adds hook
 func (db *DB) AddHook(h ...contexts.Hook) {
 	db.hooks.AddHook(h...)
 }
diff --git a/core/db_test.go b/core/db_test.go
index 104c5b95..e9c2d82d 100644
--- a/core/db_test.go
+++ b/core/db_test.go
@@ -21,7 +21,7 @@ import (
 var (
 	dbtype         = flag.String("dbtype", "sqlite3", "database type")
 	dbConn         = flag.String("dbConn", "./db_test.db", "database connect string")
-	createTableSql string
+	createTableSQL string
 )
 
 func TestMain(m *testing.M) {
@@ -29,12 +29,12 @@ func TestMain(m *testing.M) {
 
 	switch *dbtype {
 	case "sqlite3", "sqlite":
-		createTableSql = "CREATE TABLE IF NOT EXISTS `user` (`id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `name` TEXT NULL, " +
+		createTableSQL = "CREATE TABLE IF NOT EXISTS `user` (`id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `name` TEXT NULL, " +
 			"`title` TEXT NULL, `age` FLOAT NULL, `alias` TEXT NULL, `nick_name` TEXT NULL, `created` datetime);"
 	case "mysql":
 		fallthrough
 	default:
-		createTableSql = "CREATE TABLE IF NOT EXISTS `user` (`id` INTEGER PRIMARY KEY AUTO_INCREMENT NOT NULL, `name` TEXT NULL, " +
+		createTableSQL = "CREATE TABLE IF NOT EXISTS `user` (`id` INTEGER PRIMARY KEY AUTO_INCREMENT NOT NULL, `name` TEXT NULL, " +
 			"`title` TEXT NULL, `age` FLOAT NULL, `alias` TEXT NULL, `nick_name` TEXT NULL, `created` datetime);"
 	}
 
@@ -66,7 +66,7 @@ func BenchmarkOriQuery(b *testing.B) {
 	}
 	defer db.Close()
 
-	_, err = db.Exec(createTableSql)
+	_, err = db.Exec(createTableSQL)
 	if err != nil {
 		b.Error(err)
 	}
@@ -121,7 +121,7 @@ func BenchmarkStructQuery(b *testing.B) {
 	}
 	defer db.Close()
 
-	_, err = db.Exec(createTableSql)
+	_, err = db.Exec(createTableSQL)
 	if err != nil {
 		b.Error(err)
 	}
@@ -166,7 +166,7 @@ func BenchmarkStruct2Query(b *testing.B) {
 	}
 	defer db.Close()
 
-	_, err = db.Exec(createTableSql)
+	_, err = db.Exec(createTableSQL)
 	if err != nil {
 		b.Error(err)
 	}
@@ -212,7 +212,7 @@ func BenchmarkSliceInterfaceQuery(b *testing.B) {
 	}
 	defer db.Close()
 
-	_, err = db.Exec(createTableSql)
+	_, err = db.Exec(createTableSQL)
 	if err != nil {
 		b.Error(err)
 	}
@@ -270,7 +270,7 @@ func BenchmarkSliceInterfaceQuery(b *testing.B) {
 	}
 	defer db.Close()
 
-	_, err = db.Exec(createTableSql)
+	_, err = db.Exec(createTableSQL)
 	if err != nil {
 		b.Error(err)
 	}
@@ -321,7 +321,7 @@ func BenchmarkSliceStringQuery(b *testing.B) {
 	}
 	defer db.Close()
 
-	_, err = db.Exec(createTableSql)
+	_, err = db.Exec(createTableSQL)
 	if err != nil {
 		b.Error(err)
 	}
@@ -372,7 +372,7 @@ func BenchmarkMapInterfaceQuery(b *testing.B) {
 	}
 	defer db.Close()
 
-	_, err = db.Exec(createTableSql)
+	_, err = db.Exec(createTableSQL)
 	if err != nil {
 		b.Error(err)
 	}
@@ -426,7 +426,7 @@ func BenchmarkMapInterfaceQuery(b *testing.B) {
 	}
 	defer db.Close()
 
-	_, err = db.Exec(createTableSql)
+	_, err = db.Exec(createTableSQL)
 	if err != nil {
 		b.Error(err)
 	}
@@ -473,7 +473,7 @@ func BenchmarkMapStringQuery(b *testing.B) {
 	}
 	defer db.Close()
 
-	_, err = db.Exec(createTableSql)
+	_, err = db.Exec(createTableSQL)
 	if err != nil {
 		b.Error(err)
 	}
@@ -519,7 +519,7 @@ func BenchmarkExec(b *testing.B) {
 	}
 	defer db.Close()
 
-	_, err = db.Exec(createTableSql)
+	_, err = db.Exec(createTableSQL)
 	if err != nil {
 		b.Error(err)
 	}
@@ -544,7 +544,7 @@ func BenchmarkExecMap(b *testing.B) {
 	}
 	defer db.Close()
 
-	_, err = db.Exec(createTableSql)
+	_, err = db.Exec(createTableSQL)
 	if err != nil {
 		b.Error(err)
 	}
@@ -577,7 +577,7 @@ func TestExecMap(t *testing.T) {
 	}
 	defer db.Close()
 
-	_, err = db.Exec(createTableSql)
+	_, err = db.Exec(createTableSQL)
 	if err != nil {
 		t.Error(err)
 	}
@@ -620,7 +620,7 @@ func TestExecStruct(t *testing.T) {
 	}
 	defer db.Close()
 
-	_, err = db.Exec(createTableSql)
+	_, err = db.Exec(createTableSQL)
 	if err != nil {
 		t.Error(err)
 	}
@@ -663,7 +663,7 @@ func BenchmarkExecStruct(b *testing.B) {
 	}
 	defer db.Close()
 
-	_, err = db.Exec(createTableSql)
+	_, err = db.Exec(createTableSQL)
 	if err != nil {
 		b.Error(err)
 	}
diff --git a/core/rows.go b/core/rows.go
index a1e8bfbc..c15a59a3 100644
--- a/core/rows.go
+++ b/core/rows.go
@@ -11,11 +11,13 @@ import (
 	"sync"
 )
 
+// Rows represents rows of table
 type Rows struct {
 	*sql.Rows
 	db *DB
 }
 
+// ToMapString returns all records
 func (rs *Rows) ToMapString() ([]map[string]string, error) {
 	cols, err := rs.Columns()
 	if err != nil {
@@ -34,7 +36,7 @@ func (rs *Rows) ToMapString() ([]map[string]string, error) {
 	return results, nil
 }
 
-// scan data to a struct's pointer according field index
+// ScanStructByIndex scan data to a struct's pointer according field index
 func (rs *Rows) ScanStructByIndex(dest ...interface{}) error {
 	if len(dest) == 0 {
 		return errors.New("at least one struct")
@@ -94,7 +96,7 @@ func fieldByName(v reflect.Value, name string) reflect.Value {
 	return reflect.Zero(t)
 }
 
-// scan data to a struct's pointer according field name
+// ScanStructByName scan data to a struct's pointer according field name
 func (rs *Rows) ScanStructByName(dest interface{}) error {
 	vv := reflect.ValueOf(dest)
 	if vv.Kind() != reflect.Ptr || vv.Elem().Kind() != reflect.Struct {
@@ -120,7 +122,7 @@ func (rs *Rows) ScanStructByName(dest interface{}) error {
 	return rs.Rows.Scan(newDest...)
 }
 
-// scan data to a slice's pointer, slice's length should equal to columns' number
+// ScanSlice scan data to a slice's pointer, slice's length should equal to columns' number
 func (rs *Rows) ScanSlice(dest interface{}) error {
 	vv := reflect.ValueOf(dest)
 	if vv.Kind() != reflect.Ptr || vv.Elem().Kind() != reflect.Slice {
@@ -155,7 +157,7 @@ func (rs *Rows) ScanSlice(dest interface{}) error {
 	return nil
 }
 
-// scan data to a map's pointer
+// ScanMap scan data to a map's pointer
 func (rs *Rows) ScanMap(dest interface{}) error {
 	vv := reflect.ValueOf(dest)
 	if vv.Kind() != reflect.Ptr || vv.Elem().Kind() != reflect.Map {
@@ -187,6 +189,7 @@ func (rs *Rows) ScanMap(dest interface{}) error {
 	return nil
 }
 
+// Row reprents a row of  a tab
 type Row struct {
 	rows *Rows
 	// One of these two will be non-nil:
@@ -205,6 +208,7 @@ func NewRow(rows *Rows, err error) *Row {
 	return &Row{rows, err}
 }
 
+// Columns returns all columns of the row
 func (row *Row) Columns() ([]string, error) {
 	if row.err != nil {
 		return nil, row.err
@@ -212,6 +216,7 @@ func (row *Row) Columns() ([]string, error) {
 	return row.rows.Columns()
 }
 
+// Scan retrieves all row column values
 func (row *Row) Scan(dest ...interface{}) error {
 	if row.err != nil {
 		return row.err
@@ -238,6 +243,7 @@ func (row *Row) Scan(dest ...interface{}) error {
 	return row.rows.Close()
 }
 
+// ScanStructByName retrieves all row column values into a struct
 func (row *Row) ScanStructByName(dest interface{}) error {
 	if row.err != nil {
 		return row.err
@@ -258,6 +264,7 @@ func (row *Row) ScanStructByName(dest interface{}) error {
 	return row.rows.Close()
 }
 
+// ScanStructByIndex retrieves all row column values into a struct
 func (row *Row) ScanStructByIndex(dest interface{}) error {
 	if row.err != nil {
 		return row.err
@@ -278,7 +285,7 @@ func (row *Row) ScanStructByIndex(dest interface{}) error {
 	return row.rows.Close()
 }
 
-// scan data to a slice's pointer, slice's length should equal to columns' number
+// ScanSlice scan data to a slice's pointer, slice's length should equal to columns' number
 func (row *Row) ScanSlice(dest interface{}) error {
 	if row.err != nil {
 		return row.err
@@ -300,7 +307,7 @@ func (row *Row) ScanSlice(dest interface{}) error {
 	return row.rows.Close()
 }
 
-// scan data to a map's pointer
+// ScanMap scan data to a map's pointer
 func (row *Row) ScanMap(dest interface{}) error {
 	if row.err != nil {
 		return row.err
@@ -322,6 +329,7 @@ func (row *Row) ScanMap(dest interface{}) error {
 	return row.rows.Close()
 }
 
+// ToMapString returns all clumns of this record
 func (row *Row) ToMapString() (map[string]string, error) {
 	cols, err := row.Columns()
 	if err != nil {
diff --git a/core/scan.go b/core/scan.go
index 897b5341..1e7e4525 100644
--- a/core/scan.go
+++ b/core/scan.go
@@ -10,12 +10,14 @@ import (
 	"time"
 )
 
+// NullTime defines a customize type NullTime
 type NullTime time.Time
 
 var (
 	_ driver.Valuer = NullTime{}
 )
 
+// Scan implements driver.Valuer
 func (ns *NullTime) Scan(value interface{}) error {
 	if value == nil {
 		return nil
@@ -58,9 +60,11 @@ func convertTime(dest *NullTime, src interface{}) error {
 	return nil
 }
 
+// EmptyScanner represents an empty scanner
 type EmptyScanner struct {
 }
 
+// Scan implements
 func (EmptyScanner) Scan(src interface{}) error {
 	return nil
 }
diff --git a/core/stmt.go b/core/stmt.go
index d46ac9c6..260843d5 100644
--- a/core/stmt.go
+++ b/core/stmt.go
@@ -21,6 +21,7 @@ type Stmt struct {
 	query string
 }
 
+// PrepareContext creates a prepare statement
 func (db *DB) PrepareContext(ctx context.Context, query string) (*Stmt, error) {
 	names := make(map[string]int)
 	var i int
@@ -42,10 +43,12 @@ func (db *DB) PrepareContext(ctx context.Context, query string) (*Stmt, error) {
 	return &Stmt{stmt, db, names, query}, nil
 }
 
+// Prepare creates a prepare statement
 func (db *DB) Prepare(query string) (*Stmt, error) {
 	return db.PrepareContext(context.Background(), query)
 }
 
+// ExecMapContext execute with map
 func (s *Stmt) ExecMapContext(ctx context.Context, mp interface{}) (sql.Result, error) {
 	vv := reflect.ValueOf(mp)
 	if vv.Kind() != reflect.Ptr || vv.Elem().Kind() != reflect.Map {
@@ -59,10 +62,12 @@ func (s *Stmt) ExecMapContext(ctx context.Context, mp interface{}) (sql.Result,
 	return s.ExecContext(ctx, args...)
 }
 
+// ExecMap executes with map
 func (s *Stmt) ExecMap(mp interface{}) (sql.Result, error) {
 	return s.ExecMapContext(context.Background(), mp)
 }
 
+// ExecStructContext executes with struct
 func (s *Stmt) ExecStructContext(ctx context.Context, st interface{}) (sql.Result, error) {
 	vv := reflect.ValueOf(st)
 	if vv.Kind() != reflect.Ptr || vv.Elem().Kind() != reflect.Struct {
@@ -76,10 +81,12 @@ func (s *Stmt) ExecStructContext(ctx context.Context, st interface{}) (sql.Resul
 	return s.ExecContext(ctx, args...)
 }
 
+// ExecStruct executes with struct
 func (s *Stmt) ExecStruct(st interface{}) (sql.Result, error) {
 	return s.ExecStructContext(context.Background(), st)
 }
 
+// ExecContext with args
 func (s *Stmt) ExecContext(ctx context.Context, args ...interface{}) (sql.Result, error) {
 	hookCtx := contexts.NewContextHook(ctx, s.query, args)
 	ctx, err := s.db.beforeProcess(hookCtx)
@@ -94,6 +101,7 @@ func (s *Stmt) ExecContext(ctx context.Context, args ...interface{}) (sql.Result
 	return res, nil
 }
 
+// QueryContext query with args
 func (s *Stmt) QueryContext(ctx context.Context, args ...interface{}) (*Rows, error) {
 	hookCtx := contexts.NewContextHook(ctx, s.query, args)
 	ctx, err := s.db.beforeProcess(hookCtx)
@@ -108,10 +116,12 @@ func (s *Stmt) QueryContext(ctx context.Context, args ...interface{}) (*Rows, er
 	return &Rows{rows, s.db}, nil
 }
 
+// Query query with args
 func (s *Stmt) Query(args ...interface{}) (*Rows, error) {
 	return s.QueryContext(context.Background(), args...)
 }
 
+// QueryMapContext query with map
 func (s *Stmt) QueryMapContext(ctx context.Context, mp interface{}) (*Rows, error) {
 	vv := reflect.ValueOf(mp)
 	if vv.Kind() != reflect.Ptr || vv.Elem().Kind() != reflect.Map {
@@ -126,10 +136,12 @@ func (s *Stmt) QueryMapContext(ctx context.Context, mp interface{}) (*Rows, erro
 	return s.QueryContext(ctx, args...)
 }
 
+// QueryMap query with map
 func (s *Stmt) QueryMap(mp interface{}) (*Rows, error) {
 	return s.QueryMapContext(context.Background(), mp)
 }
 
+// QueryStructContext query with struct
 func (s *Stmt) QueryStructContext(ctx context.Context, st interface{}) (*Rows, error) {
 	vv := reflect.ValueOf(st)
 	if vv.Kind() != reflect.Ptr || vv.Elem().Kind() != reflect.Struct {
@@ -144,19 +156,23 @@ func (s *Stmt) QueryStructContext(ctx context.Context, st interface{}) (*Rows, e
 	return s.QueryContext(ctx, args...)
 }
 
+// QueryStruct query with struct
 func (s *Stmt) QueryStruct(st interface{}) (*Rows, error) {
 	return s.QueryStructContext(context.Background(), st)
 }
 
+// QueryRowContext query row with args
 func (s *Stmt) QueryRowContext(ctx context.Context, args ...interface{}) *Row {
 	rows, err := s.QueryContext(ctx, args...)
 	return &Row{rows, err}
 }
 
+// QueryRow query row with args
 func (s *Stmt) QueryRow(args ...interface{}) *Row {
 	return s.QueryRowContext(context.Background(), args...)
 }
 
+// QueryRowMapContext query row with map
 func (s *Stmt) QueryRowMapContext(ctx context.Context, mp interface{}) *Row {
 	vv := reflect.ValueOf(mp)
 	if vv.Kind() != reflect.Ptr || vv.Elem().Kind() != reflect.Map {
@@ -171,10 +187,12 @@ func (s *Stmt) QueryRowMapContext(ctx context.Context, mp interface{}) *Row {
 	return s.QueryRowContext(ctx, args...)
 }
 
+// QueryRowMap query row with map
 func (s *Stmt) QueryRowMap(mp interface{}) *Row {
 	return s.QueryRowMapContext(context.Background(), mp)
 }
 
+// QueryRowStructContext query row with struct
 func (s *Stmt) QueryRowStructContext(ctx context.Context, st interface{}) *Row {
 	vv := reflect.ValueOf(st)
 	if vv.Kind() != reflect.Ptr || vv.Elem().Kind() != reflect.Struct {
@@ -189,6 +207,7 @@ func (s *Stmt) QueryRowStructContext(ctx context.Context, st interface{}) *Row {
 	return s.QueryRowContext(ctx, args...)
 }
 
+// QueryRowStruct query row with struct
 func (s *Stmt) QueryRowStruct(st interface{}) *Row {
 	return s.QueryRowStructContext(context.Background(), st)
 }
diff --git a/core/tx.go b/core/tx.go
index 24d548b3..a2f745f8 100644
--- a/core/tx.go
+++ b/core/tx.go
@@ -51,10 +51,7 @@ func (tx *Tx) Commit() error {
 	}
 	err = tx.Tx.Commit()
 	hookCtx.End(ctx, nil, err)
-	if err := tx.db.afterProcess(hookCtx); err != nil {
-		return err
-	}
-	return nil
+	return tx.db.afterProcess(hookCtx)
 }
 
 // Rollback rollback the transaction
@@ -66,10 +63,7 @@ func (tx *Tx) Rollback() error {
 	}
 	err = tx.Tx.Rollback()
 	hookCtx.End(ctx, nil, err)
-	if err := tx.db.afterProcess(hookCtx); err != nil {
-		return err
-	}
-	return nil
+	return tx.db.afterProcess(hookCtx)
 }
 
 // PrepareContext prepare the query
diff --git a/integrations/session_delete_test.go b/integrations/session_delete_test.go
index f3565963..cc7e861d 100644
--- a/integrations/session_delete_test.go
+++ b/integrations/session_delete_test.go
@@ -97,6 +97,7 @@ func TestDeleted(t *testing.T) {
 	// Test normal Find()
 	var records1 []Deleted
 	err = testEngine.Where("`"+testEngine.GetColumnMapper().Obj2Table("Id")+"` > 0").Find(&records1, &Deleted{})
+	assert.NoError(t, err)
 	assert.EqualValues(t, 3, len(records1))
 
 	// Test normal Get()
@@ -132,6 +133,7 @@ func TestDeleted(t *testing.T) {
 	record2 := &Deleted{}
 	has, err = testEngine.ID(2).Get(record2)
 	assert.NoError(t, err)
+	assert.True(t, has)
 	assert.True(t, record2.DeletedAt.IsZero())
 
 	// Test find all records whatever `deleted`.
diff --git a/internal/statements/cache.go b/internal/statements/cache.go
index cb33df08..669cd018 100644
--- a/internal/statements/cache.go
+++ b/internal/statements/cache.go
@@ -12,6 +12,7 @@ import (
 	"xorm.io/xorm/schemas"
 )
 
+// ConvertIDSQL converts SQL with id
 func (statement *Statement) ConvertIDSQL(sqlStr string) string {
 	if statement.RefTable != nil {
 		cols := statement.RefTable.PKColumns()
@@ -37,6 +38,7 @@ func (statement *Statement) ConvertIDSQL(sqlStr string) string {
 	return ""
 }
 
+// ConvertUpdateSQL converts update SQL
 func (statement *Statement) ConvertUpdateSQL(sqlStr string) (string, string) {
 	if statement.RefTable == nil || len(statement.RefTable.PrimaryKeys) != 1 {
 		return "", ""
diff --git a/internal/statements/query.go b/internal/statements/query.go
index ab3021bf..f1b36770 100644
--- a/internal/statements/query.go
+++ b/internal/statements/query.go
@@ -14,6 +14,7 @@ import (
 	"xorm.io/xorm/schemas"
 )
 
+// GenQuerySQL generate query SQL
 func (statement *Statement) GenQuerySQL(sqlOrArgs ...interface{}) (string, []interface{}, error) {
 	if len(sqlOrArgs) > 0 {
 		return statement.ConvertSQLOrArgs(sqlOrArgs...)
@@ -72,6 +73,7 @@ func (statement *Statement) GenQuerySQL(sqlOrArgs ...interface{}) (string, []int
 	return sqlStr, args, nil
 }
 
+// GenSumSQL generates sum SQL
 func (statement *Statement) GenSumSQL(bean interface{}, columns ...string) (string, []interface{}, error) {
 	if statement.RawSQL != "" {
 		return statement.GenRawSQL(), statement.RawParams, nil
@@ -102,6 +104,7 @@ func (statement *Statement) GenSumSQL(bean interface{}, columns ...string) (stri
 	return sqlStr, append(statement.joinArgs, condArgs...), nil
 }
 
+// GenGetSQL generates Get SQL
 func (statement *Statement) GenGetSQL(bean interface{}) (string, []interface{}, error) {
 	v := rValue(bean)
 	isStruct := v.Kind() == reflect.Struct
@@ -316,6 +319,7 @@ func (statement *Statement) genSelectSQL(columnStr string, needLimit, needOrderB
 	return buf.String(), condArgs, nil
 }
 
+// GenExistSQL generates Exist SQL
 func (statement *Statement) GenExistSQL(bean ...interface{}) (string, []interface{}, error) {
 	if statement.RawSQL != "" {
 		return statement.GenRawSQL(), statement.RawParams, nil
@@ -385,6 +389,7 @@ func (statement *Statement) GenExistSQL(bean ...interface{}) (string, []interfac
 	return sqlStr, args, nil
 }
 
+// GenFindSQL generates Find SQL
 func (statement *Statement) GenFindSQL(autoCond builder.Cond) (string, []interface{}, error) {
 	if statement.RawSQL != "" {
 		return statement.GenRawSQL(), statement.RawParams, nil
diff --git a/internal/statements/statement.go b/internal/statements/statement.go
index 87f785ae..3dd036a6 100644
--- a/internal/statements/statement.go
+++ b/internal/statements/statement.go
@@ -90,14 +90,11 @@ func NewStatement(dialect dialects.Dialect, tagParser *tags.Parser, defaultTimeZ
 	return statement
 }
 
+// SetTableName set table name
 func (statement *Statement) SetTableName(tableName string) {
 	statement.tableName = tableName
 }
 
-func (statement *Statement) omitStr() string {
-	return statement.dialect.Quoter().Join(statement.OmitColumnMap, " ,")
-}
-
 // GenRawSQL generates correct raw sql
 func (statement *Statement) GenRawSQL() string {
 	return statement.ReplaceQuote(statement.RawSQL)
@@ -112,6 +109,7 @@ func (statement *Statement) GenCondSQL(condOrBuilder interface{}) (string, []int
 	return statement.ReplaceQuote(condSQL), condArgs, nil
 }
 
+// ReplaceQuote replace sql key words with quote
 func (statement *Statement) ReplaceQuote(sql string) string {
 	if sql == "" || statement.dialect.URI().DBType == schemas.MYSQL ||
 		statement.dialect.URI().DBType == schemas.SQLITE {
@@ -591,7 +589,7 @@ func (statement *Statement) Having(conditions string) *Statement {
 	return statement
 }
 
-// Unscoped always disable struct tag "deleted"
+// SetUnscoped always disable struct tag "deleted"
 func (statement *Statement) SetUnscoped() *Statement {
 	statement.unscoped = true
 	return statement
@@ -923,10 +921,7 @@ func (statement *Statement) mergeConds(bean interface{}) error {
 		statement.cond = statement.cond.And(autoCond)
 	}
 
-	if err := statement.ProcessIDParam(); err != nil {
-		return err
-	}
-	return nil
+	return statement.ProcessIDParam()
 }
 
 // GenConds generates conditions
diff --git a/internal/statements/statement_args.go b/internal/statements/statement_args.go
index dc14467d..64089c1e 100644
--- a/internal/statements/statement_args.go
+++ b/internal/statements/statement_args.go
@@ -77,6 +77,7 @@ func convertArg(arg interface{}, convertFunc func(string) string) string {
 
 const insertSelectPlaceHolder = true
 
+// WriteArg writes an arg
 func (statement *Statement) WriteArg(w *builder.BytesWriter, arg interface{}) error {
 	switch argv := arg.(type) {
 	case *builder.Builder:
@@ -116,6 +117,7 @@ func (statement *Statement) WriteArg(w *builder.BytesWriter, arg interface{}) er
 	return nil
 }
 
+// WriteArgs writes args
 func (statement *Statement) WriteArgs(w *builder.BytesWriter, args []interface{}) error {
 	for i, arg := range args {
 		if err := statement.WriteArg(w, arg); err != nil {
diff --git a/names/mapper.go b/names/mapper.go
index 79add76e..b0ce8076 100644
--- a/names/mapper.go
+++ b/names/mapper.go
@@ -16,6 +16,7 @@ type Mapper interface {
 	Table2Obj(string) string
 }
 
+// CacheMapper represents a cache mapper
 type CacheMapper struct {
 	oriMapper      Mapper
 	obj2tableCache map[string]string
@@ -24,12 +25,14 @@ type CacheMapper struct {
 	table2objMutex sync.RWMutex
 }
 
+// NewCacheMapper creates a cache mapper
 func NewCacheMapper(mapper Mapper) *CacheMapper {
 	return &CacheMapper{oriMapper: mapper, obj2tableCache: make(map[string]string),
 		table2objCache: make(map[string]string),
 	}
 }
 
+// Obj2Table implements Mapper
 func (m *CacheMapper) Obj2Table(o string) string {
 	m.obj2tableMutex.RLock()
 	t, ok := m.obj2tableCache[o]
@@ -45,6 +48,7 @@ func (m *CacheMapper) Obj2Table(o string) string {
 	return t
 }
 
+// Table2Obj implements Mapper
 func (m *CacheMapper) Table2Obj(t string) string {
 	m.table2objMutex.RLock()
 	o, ok := m.table2objCache[t]
@@ -60,15 +64,17 @@ func (m *CacheMapper) Table2Obj(t string) string {
 	return o
 }
 
-// SameMapper implements IMapper and provides same name between struct and
+// SameMapper implements Mapper and provides same name between struct and
 // database table
 type SameMapper struct {
 }
 
+// Obj2Table implements Mapper
 func (m SameMapper) Obj2Table(o string) string {
 	return o
 }
 
+// Table2Obj implements Mapper
 func (m SameMapper) Table2Obj(t string) string {
 	return t
 }
@@ -98,6 +104,7 @@ func snakeCasedName(name string) string {
 	return b2s(newstr)
 }
 
+// Obj2Table implements Mapper
 func (mapper SnakeMapper) Obj2Table(name string) string {
 	return snakeCasedName(name)
 }
@@ -127,6 +134,7 @@ func titleCasedName(name string) string {
 	return b2s(newstr)
 }
 
+// Table2Obj implements Mapper
 func (mapper SnakeMapper) Table2Obj(name string) string {
 	return titleCasedName(name)
 }
@@ -168,10 +176,12 @@ func gonicCasedName(name string) string {
 	return strings.ToLower(string(newstr))
 }
 
+// Obj2Table implements Mapper
 func (mapper GonicMapper) Obj2Table(name string) string {
 	return gonicCasedName(name)
 }
 
+// Table2Obj implements Mapper
 func (mapper GonicMapper) Table2Obj(name string) string {
 	newstr := make([]rune, 0)
 
@@ -234,14 +244,17 @@ type PrefixMapper struct {
 	Prefix string
 }
 
+// Obj2Table implements Mapper
 func (mapper PrefixMapper) Obj2Table(name string) string {
 	return mapper.Prefix + mapper.Mapper.Obj2Table(name)
 }
 
+// Table2Obj implements Mapper
 func (mapper PrefixMapper) Table2Obj(name string) string {
 	return mapper.Mapper.Table2Obj(name[len(mapper.Prefix):])
 }
 
+// NewPrefixMapper creates a prefix mapper
 func NewPrefixMapper(mapper Mapper, prefix string) PrefixMapper {
 	return PrefixMapper{mapper, prefix}
 }
@@ -252,14 +265,17 @@ type SuffixMapper struct {
 	Suffix string
 }
 
+// Obj2Table implements Mapper
 func (mapper SuffixMapper) Obj2Table(name string) string {
 	return mapper.Mapper.Obj2Table(name) + mapper.Suffix
 }
 
+// Table2Obj implements Mapper
 func (mapper SuffixMapper) Table2Obj(name string) string {
 	return mapper.Mapper.Table2Obj(name[:len(name)-len(mapper.Suffix)])
 }
 
+// NewSuffixMapper creates a suffix mapper
 func NewSuffixMapper(mapper Mapper, suffix string) SuffixMapper {
 	return SuffixMapper{mapper, suffix}
 }
diff --git a/names/table_name.go b/names/table_name.go
index 0afb1ae3..cc0e9274 100644
--- a/names/table_name.go
+++ b/names/table_name.go
@@ -19,6 +19,7 @@ var (
 	tvCache     sync.Map
 )
 
+// GetTableName returns table name
 func GetTableName(mapper Mapper, v reflect.Value) string {
 	if v.Type().Implements(tpTableName) {
 		return v.Interface().(TableName).TableName()
diff --git a/schemas/column.go b/schemas/column.go
index 4f32afab..5808b84d 100644
--- a/schemas/column.go
+++ b/schemas/column.go
@@ -13,6 +13,7 @@ import (
 	"time"
 )
 
+// enumerates all database mapping way
 const (
 	TWOSIDES = iota + 1
 	ONLYTODB
diff --git a/schemas/index.go b/schemas/index.go
index 9541250f..8f31af52 100644
--- a/schemas/index.go
+++ b/schemas/index.go
@@ -28,6 +28,7 @@ func NewIndex(name string, indexType int) *Index {
 	return &Index{true, name, indexType, make([]string, 0)}
 }
 
+// XName returns the special index name for the table
 func (index *Index) XName(tableName string) string {
 	if !strings.HasPrefix(index.Name, "UQE_") &&
 		!strings.HasPrefix(index.Name, "IDX_") {
@@ -43,11 +44,10 @@ func (index *Index) XName(tableName string) string {
 
 // AddColumn add columns which will be composite index
 func (index *Index) AddColumn(cols ...string) {
-	for _, col := range cols {
-		index.Cols = append(index.Cols, col)
-	}
+	index.Cols = append(index.Cols, cols...)
 }
 
+// Equal return true if the two Index is equal
 func (index *Index) Equal(dst *Index) bool {
 	if index.Type != dst.Type {
 		return false
diff --git a/schemas/pk.go b/schemas/pk.go
index 03916b44..da3c7899 100644
--- a/schemas/pk.go
+++ b/schemas/pk.go
@@ -11,13 +11,16 @@ import (
 	"xorm.io/xorm/internal/utils"
 )
 
+// PK represents primary key values
 type PK []interface{}
 
+// NewPK creates primay keys
 func NewPK(pks ...interface{}) *PK {
 	p := PK(pks)
 	return &p
 }
 
+// IsZero return true if primay keys are zero
 func (p *PK) IsZero() bool {
 	for _, k := range *p {
 		if utils.IsZero(k) {
@@ -27,6 +30,7 @@ func (p *PK) IsZero() bool {
 	return false
 }
 
+// ToString convert to SQL string
 func (p *PK) ToString() (string, error) {
 	buf := new(bytes.Buffer)
 	enc := gob.NewEncoder(buf)
@@ -34,6 +38,7 @@ func (p *PK) ToString() (string, error) {
 	return buf.String(), err
 }
 
+// FromString reads content to load primary keys
 func (p *PK) FromString(content string) error {
 	dec := gob.NewDecoder(bytes.NewBufferString(content))
 	err := dec.Decode(p)
diff --git a/schemas/quote.go b/schemas/quote.go
index a0070048..71040ad9 100644
--- a/schemas/quote.go
+++ b/schemas/quote.go
@@ -16,10 +16,10 @@ type Quoter struct {
 }
 
 var (
-	// AlwaysFalseReverse always think it's not a reverse word
+	// AlwaysNoReserve always think it's not a reverse word
 	AlwaysNoReserve = func(string) bool { return false }
 
-	// AlwaysReverse always reverse the word
+	// AlwaysReserve always reverse the word
 	AlwaysReserve = func(string) bool { return true }
 
 	// CommanQuoteMark represnets the common quote mark
@@ -29,10 +29,12 @@ var (
 	CommonQuoter = Quoter{CommanQuoteMark, CommanQuoteMark, AlwaysReserve}
 )
 
+// IsEmpty return true if no prefix and suffix
 func (q Quoter) IsEmpty() bool {
 	return q.Prefix == 0 && q.Suffix == 0
 }
 
+// Quote quote a string
 func (q Quoter) Quote(s string) string {
 	var buf strings.Builder
 	q.QuoteTo(&buf, s)
@@ -59,12 +61,14 @@ func (q Quoter) Trim(s string) string {
 	return buf.String()
 }
 
+// Join joins a slice with quoters
 func (q Quoter) Join(a []string, sep string) string {
 	var b strings.Builder
 	q.JoinWrite(&b, a, sep)
 	return b.String()
 }
 
+// JoinWrite writes quoted content to a builder
 func (q Quoter) JoinWrite(b *strings.Builder, a []string, sep string) error {
 	if len(a) == 0 {
 		return nil
diff --git a/schemas/table.go b/schemas/table.go
index 7ca9531f..bfa517aa 100644
--- a/schemas/table.go
+++ b/schemas/table.go
@@ -90,23 +90,28 @@ func (table *Table) PKColumns() []*Column {
 	return columns
 }
 
+// ColumnType returns a column's type
 func (table *Table) ColumnType(name string) reflect.Type {
 	t, _ := table.Type.FieldByName(name)
 	return t.Type
 }
 
+// AutoIncrColumn returns autoincrement column
 func (table *Table) AutoIncrColumn() *Column {
 	return table.GetColumn(table.AutoIncrement)
 }
 
+// VersionColumn returns version column's information
 func (table *Table) VersionColumn() *Column {
 	return table.GetColumn(table.Version)
 }
 
+// UpdatedColumn returns updated column's information
 func (table *Table) UpdatedColumn() *Column {
 	return table.GetColumn(table.Updated)
 }
 
+// DeletedColumn returns deleted column's information
 func (table *Table) DeletedColumn() *Column {
 	return table.GetColumn(table.Deleted)
 }
diff --git a/schemas/type.go b/schemas/type.go
index c6cdfb87..fc02f015 100644
--- a/schemas/type.go
+++ b/schemas/type.go
@@ -222,53 +222,55 @@ var (
 
 // !nashtsai! treat following var as interal const values, these are used for reflect.TypeOf comparison
 var (
-	c_EMPTY_STRING       string
-	c_BOOL_DEFAULT       bool
-	c_BYTE_DEFAULT       byte
-	c_COMPLEX64_DEFAULT  complex64
-	c_COMPLEX128_DEFAULT complex128
-	c_FLOAT32_DEFAULT    float32
-	c_FLOAT64_DEFAULT    float64
-	c_INT64_DEFAULT      int64
-	c_UINT64_DEFAULT     uint64
-	c_INT32_DEFAULT      int32
-	c_UINT32_DEFAULT     uint32
-	c_INT16_DEFAULT      int16
-	c_UINT16_DEFAULT     uint16
-	c_INT8_DEFAULT       int8
-	c_UINT8_DEFAULT      uint8
-	c_INT_DEFAULT        int
-	c_UINT_DEFAULT       uint
-	c_TIME_DEFAULT       time.Time
+	emptyString       string
+	boolDefault       bool
+	byteDefault       byte
+	complex64Default  complex64
+	complex128Default complex128
+	float32Default    float32
+	float64Default    float64
+	int64Default      int64
+	uint64Default     uint64
+	int32Default      int32
+	uint32Default     uint32
+	int16Default      int16
+	uint16Default     uint16
+	int8Default       int8
+	uint8Default      uint8
+	intDefault        int
+	uintDefault       uint
+	timeDefault       time.Time
 )
 
+// enumerates all types
 var (
-	IntType   = reflect.TypeOf(c_INT_DEFAULT)
-	Int8Type  = reflect.TypeOf(c_INT8_DEFAULT)
-	Int16Type = reflect.TypeOf(c_INT16_DEFAULT)
-	Int32Type = reflect.TypeOf(c_INT32_DEFAULT)
-	Int64Type = reflect.TypeOf(c_INT64_DEFAULT)
+	IntType   = reflect.TypeOf(intDefault)
+	Int8Type  = reflect.TypeOf(int8Default)
+	Int16Type = reflect.TypeOf(int16Default)
+	Int32Type = reflect.TypeOf(int32Default)
+	Int64Type = reflect.TypeOf(int64Default)
 
-	UintType   = reflect.TypeOf(c_UINT_DEFAULT)
-	Uint8Type  = reflect.TypeOf(c_UINT8_DEFAULT)
-	Uint16Type = reflect.TypeOf(c_UINT16_DEFAULT)
-	Uint32Type = reflect.TypeOf(c_UINT32_DEFAULT)
-	Uint64Type = reflect.TypeOf(c_UINT64_DEFAULT)
+	UintType   = reflect.TypeOf(uintDefault)
+	Uint8Type  = reflect.TypeOf(uint8Default)
+	Uint16Type = reflect.TypeOf(uint16Default)
+	Uint32Type = reflect.TypeOf(uint32Default)
+	Uint64Type = reflect.TypeOf(uint64Default)
 
-	Float32Type = reflect.TypeOf(c_FLOAT32_DEFAULT)
-	Float64Type = reflect.TypeOf(c_FLOAT64_DEFAULT)
+	Float32Type = reflect.TypeOf(float32Default)
+	Float64Type = reflect.TypeOf(float64Default)
 
-	Complex64Type  = reflect.TypeOf(c_COMPLEX64_DEFAULT)
-	Complex128Type = reflect.TypeOf(c_COMPLEX128_DEFAULT)
+	Complex64Type  = reflect.TypeOf(complex64Default)
+	Complex128Type = reflect.TypeOf(complex128Default)
 
-	StringType = reflect.TypeOf(c_EMPTY_STRING)
-	BoolType   = reflect.TypeOf(c_BOOL_DEFAULT)
-	ByteType   = reflect.TypeOf(c_BYTE_DEFAULT)
+	StringType = reflect.TypeOf(emptyString)
+	BoolType   = reflect.TypeOf(boolDefault)
+	ByteType   = reflect.TypeOf(byteDefault)
 	BytesType  = reflect.SliceOf(ByteType)
 
-	TimeType = reflect.TypeOf(c_TIME_DEFAULT)
+	TimeType = reflect.TypeOf(timeDefault)
 )
 
+// enumerates all types
 var (
 	PtrIntType   = reflect.PtrTo(IntType)
 	PtrInt8Type  = reflect.PtrTo(Int8Type)
@@ -313,7 +315,7 @@ func Type2SQLType(t reflect.Type) (st SQLType) {
 	case reflect.Complex64, reflect.Complex128:
 		st = SQLType{Varchar, 64, 0}
 	case reflect.Array, reflect.Slice, reflect.Map:
-		if t.Elem() == reflect.TypeOf(c_BYTE_DEFAULT) {
+		if t.Elem() == reflect.TypeOf(byteDefault) {
 			st = SQLType{Blob, 0, 0}
 		} else {
 			st = SQLType{Text, 0, 0}
@@ -337,7 +339,7 @@ func Type2SQLType(t reflect.Type) (st SQLType) {
 	return
 }
 
-// default sql type change to go types
+// SQLType2Type convert default sql type change to go types
 func SQLType2Type(st SQLType) reflect.Type {
 	name := strings.ToUpper(st.Name)
 	switch name {
@@ -356,7 +358,7 @@ func SQLType2Type(st SQLType) reflect.Type {
 	case Bool:
 		return reflect.TypeOf(true)
 	case DateTime, Date, Time, TimeStamp, TimeStampz, SmallDateTime, Year:
-		return reflect.TypeOf(c_TIME_DEFAULT)
+		return reflect.TypeOf(timeDefault)
 	case Decimal, Numeric, Money, SmallMoney:
 		return reflect.TypeOf("")
 	default:
diff --git a/tags/parser.go b/tags/parser.go
index 45dd6d9d..5ad67b53 100644
--- a/tags/parser.go
+++ b/tags/parser.go
@@ -21,9 +21,11 @@ import (
 )
 
 var (
+	// ErrUnsupportedType represents an unsupported type error
 	ErrUnsupportedType = errors.New("Unsupported type")
 )
 
+// Parser represents a parser for xorm tag
 type Parser struct {
 	identifier   string
 	dialect      dialects.Dialect
@@ -34,6 +36,7 @@ type Parser struct {
 	tableCache   sync.Map // map[reflect.Type]*schemas.Table
 }
 
+// NewParser creates a tag parser
 func NewParser(identifier string, dialect dialects.Dialect, tableMapper, columnMapper names.Mapper, cacherMgr *caches.Manager) *Parser {
 	return &Parser{
 		identifier:   identifier,
@@ -45,29 +48,35 @@ func NewParser(identifier string, dialect dialects.Dialect, tableMapper, columnM
 	}
 }
 
+// GetTableMapper returns table mapper
 func (parser *Parser) GetTableMapper() names.Mapper {
 	return parser.tableMapper
 }
 
+// SetTableMapper sets table mapper
 func (parser *Parser) SetTableMapper(mapper names.Mapper) {
 	parser.ClearCaches()
 	parser.tableMapper = mapper
 }
 
+// GetColumnMapper returns column mapper
 func (parser *Parser) GetColumnMapper() names.Mapper {
 	return parser.columnMapper
 }
 
+// SetColumnMapper sets column mapper
 func (parser *Parser) SetColumnMapper(mapper names.Mapper) {
 	parser.ClearCaches()
 	parser.columnMapper = mapper
 }
 
+// SetIdentifier sets tag identifier
 func (parser *Parser) SetIdentifier(identifier string) {
 	parser.ClearCaches()
 	parser.identifier = identifier
 }
 
+// ParseWithCache parse a struct with cache
 func (parser *Parser) ParseWithCache(v reflect.Value) (*schemas.Table, error) {
 	t := v.Type()
 	tableI, ok := parser.tableCache.Load(t)