diff --git a/app/main.go b/app/main.go
index 1e28dd3..8a5ec67 100644
--- a/app/main.go
+++ b/app/main.go
@@ -24,7 +24,7 @@ func main() {
 		wait()
 	}
 	// 下面都是运行示例，因此首先把服务器的数据重新准备好
-	dtmsvr.PopulateMysql()
+	dtmsvr.PopulateMysql(true)
 	dtmsvr.MainStart()
 	if len(os.Args) == 1 { // 默认没有参数的情况下，准备好数据并启动dtmsvr即可
 		wait()
@@ -37,7 +37,7 @@ func main() {
 	}
 
 	// 下面是各类的例子
-	examples.PopulateMysql()
+	examples.PopulateMysql(true)
 	app := examples.BaseAppStartup()
 	if os.Args[1] == "xa" { // 启动xa示例
 		examples.XaSetup(app)
@@ -47,7 +47,7 @@ func main() {
 		examples.SagaFireRequest()
 	} else if os.Args[1] == "tcc" { // 启动tcc示例
 		examples.TccSetup(app)
-		examples.TccFireRequest()
+		examples.TccFireRequestNested()
 	} else if os.Args[1] == "msg" { // 启动msg示例
 		examples.MsgSetup(app)
 		examples.MsgFireRequest()
@@ -57,7 +57,7 @@ func main() {
 		examples.XaSetup(app)
 		examples.MsgSetup(app)
 		examples.SagaFireRequest()
-		examples.TccFireRequest()
+		examples.TccFireRequestNested()
 		examples.XaFireRequest()
 		examples.MsgFireRequest()
 	} else if os.Args[1] == "saga_barrier" {
diff --git a/dtmcli/tcc.go b/dtmcli/tcc.go
index 7f89d93..c7e1f83 100644
--- a/dtmcli/tcc.go
+++ b/dtmcli/tcc.go
@@ -21,6 +21,9 @@ type Tcc struct {
 type TccGlobalFunc func(tcc *Tcc) error
 
 // TccGlobalTransaction begin a tcc global transaction
+// dtm dtm服务器地址
+// gid 全局事务id
+// tccFunc tcc事务函数，里面会定义全局事务的分支
 func TccGlobalTransaction(dtm string, gid string, tccFunc TccGlobalFunc) (rerr error) {
 	data := &M{
 		"gid":        gid,
@@ -67,6 +70,7 @@ func TccFromReq(c *gin.Context) (*Tcc, error) {
 }
 
 // CallBranch call a tcc branch
+// 函数首先注册子事务的所有分支，成功后调用try分支，返回try分支的调用结果
 func (t *Tcc) CallBranch(body interface{}, tryURL string, confirmURL string, cancelURL string) (*resty.Response, error) {
 	branchID := t.NewBranchID()
 	resp, err := common.RestyClient.R().
diff --git a/dtmsvr/dtmsvr_test.go b/dtmsvr/dtmsvr_test.go
index 284c44b..e1886b8 100644
--- a/dtmsvr/dtmsvr_test.go
+++ b/dtmsvr/dtmsvr_test.go
@@ -21,8 +21,8 @@ func TestMain(m *testing.M) {
 	TransProcessedTestChan = make(chan string, 1)
 	common.InitApp(common.GetProjectDir(), &config)
 	config.Mysql["database"] = dbName
-	PopulateMysql()
-	examples.PopulateMysql()
+	PopulateMysql(false)
+	examples.PopulateMysql(false)
 	// 启动组件
 	go StartSvr()
 	app = examples.BaseAppStartup()
@@ -33,10 +33,6 @@ func TestMain(m *testing.M) {
 	examples.TccBarrierAddRoute(app)
 	examples.SagaBarrierAddRoute(app)
 
-	// 清理数据
-	e2p(dbGet().Exec("truncate trans_global").Error)
-	e2p(dbGet().Exec("truncate trans_branch").Error)
-	e2p(dbGet().Exec("truncate trans_log").Error)
 	examples.ResetXaData()
 	m.Run()
 }
diff --git a/dtmsvr/examples_test.go b/dtmsvr/examples_test.go
index 53990a7..2c2cc0f 100644
--- a/dtmsvr/examples_test.go
+++ b/dtmsvr/examples_test.go
@@ -15,5 +15,6 @@ func TestExamples(t *testing.T) {
 	assertSucceed(t, examples.SagaFireRequest())
 	assertSucceed(t, examples.TccBarrierFireRequest())
 	assertSucceed(t, examples.TccFireRequest())
+	assertSucceed(t, examples.TccFireRequestNested())
 	assertSucceed(t, examples.XaFireRequest())
 }
diff --git a/dtmsvr/main.go b/dtmsvr/main.go
index a19a61b..8bdd966 100644
--- a/dtmsvr/main.go
+++ b/dtmsvr/main.go
@@ -30,8 +30,8 @@ func StartSvr() {
 }
 
 // PopulateMysql setup mysql data
-func PopulateMysql() {
+func PopulateMysql(skipDrop bool) {
 	common.InitApp(common.GetProjectDir(), &config)
 	config.Mysql["database"] = ""
-	examples.RunSQLScript(config.Mysql, common.GetCurrentCodeDir()+"/dtmsvr.sql")
+	examples.RunSQLScript(config.Mysql, common.GetCurrentCodeDir()+"/dtmsvr.sql", skipDrop)
 }
diff --git a/examples/data.go b/examples/data.go
index 738467e..72da650 100644
--- a/examples/data.go
+++ b/examples/data.go
@@ -9,7 +9,7 @@ import (
 )
 
 // RunSQLScript 1
-func RunSQLScript(mysql map[string]string, script string) {
+func RunSQLScript(mysql map[string]string, script string, skipDrop bool) {
 	conf := map[string]string{}
 	common.MustRemarshal(mysql, &conf)
 	conf["database"] = ""
@@ -22,7 +22,7 @@ func RunSQLScript(mysql map[string]string, script string) {
 	sqls := strings.Split(string(content), ";")
 	for _, sql := range sqls {
 		s := strings.TrimSpace(sql)
-		if s == "" {
+		if s == "" || skipDrop && strings.Contains(s, "drop") {
 			continue
 		}
 		logrus.Printf("executing: '%s'", s)
@@ -31,8 +31,8 @@ func RunSQLScript(mysql map[string]string, script string) {
 }
 
 // PopulateMysql populate example mysql data
-func PopulateMysql() {
+func PopulateMysql(skipDrop bool) {
 	common.InitApp(common.GetProjectDir(), &config)
 	config.Mysql["database"] = dbName
-	RunSQLScript(config.Mysql, common.GetCurrentCodeDir()+"/examples.sql")
+	RunSQLScript(config.Mysql, common.GetCurrentCodeDir()+"/examples.sql", skipDrop)
 }
diff --git a/examples/main_tcc.go b/examples/main_tcc.go
index fa2e310..c2c79be 100644
--- a/examples/main_tcc.go
+++ b/examples/main_tcc.go
@@ -21,8 +21,8 @@ func TccSetup(app *gin.Engine) {
 	}))
 }
 
-// TccFireRequest 1
-func TccFireRequest() string {
+// TccFireRequestNested 1
+func TccFireRequestNested() string {
 	logrus.Printf("tcc transaction begin")
 	gid := dtmcli.MustGenGid(DtmServer)
 	err := dtmcli.TccGlobalTransaction(DtmServer, gid, func(tcc *dtmcli.Tcc) (rerr error) {
@@ -36,3 +36,18 @@ func TccFireRequest() string {
 	e2p(err)
 	return gid
 }
+
+// TccFireRequest 1
+func TccFireRequest() string {
+	logrus.Printf("tcc simple transaction begin")
+	gid := dtmcli.MustGenGid(DtmServer)
+	err := dtmcli.TccGlobalTransaction(DtmServer, gid, func(tcc *dtmcli.Tcc) (rerr error) {
+		res1, rerr := tcc.CallBranch(&TransReq{Amount: 30}, Busi+"/TransOut", Busi+"/TransOutConfirm", Busi+"/TransOutRevert")
+		e2p(rerr)
+		res2, rerr := tcc.CallBranch(&TransReq{Amount: 30}, Busi+"/TransIn", Busi+"/TransInConfirm", Busi+"/TransInRevert")
+		logrus.Printf("tcc returns: %s, %s", res1.String(), res2.String())
+		return
+	})
+	e2p(err)
+	return gid
+}