diff --git a/database/gdb/gdb_func.go b/database/gdb/gdb_func.go
index f9034111f..d652ad60c 100644
--- a/database/gdb/gdb_func.go
+++ b/database/gdb/gdb_func.go
@@ -772,12 +772,6 @@ func handleArguments(sql string, args []interface{}) (newSql string, newArgs []i
 					newArgs = append(newArgs, arg)
 					continue
 
-				// Special handling for gtime.Time/*gtime.Time.
-				//
-				// DO NOT use its underlying gtime.Time.Time as its argument,
-				// because the std time.Time will be converted to certain timezone
-				// according to underlying driver. And the underlying driver also
-				// converts the time.Time to string automatically as the following does.
 				case gtime.Time:
 					newArgs = append(newArgs, arg.(gtime.Time).Time)
 					continue
diff --git a/database/gdb/gdb_z_init_test.go b/database/gdb/gdb_z_init_test.go
index e4f8ba832..7a0e2e865 100644
--- a/database/gdb/gdb_z_init_test.go
+++ b/database/gdb/gdb_z_init_test.go
@@ -48,7 +48,7 @@ func init() {
 		Port:             "3306",
 		User:             TestDbUser,
 		Pass:             TestDbPass,
-		Timezone:         "Asia/Shanghai",
+		Timezone:         "Asia/Shanghai", // For calculating UT cases of datetime zones in convenience.
 		Name:             parser.GetOpt("name", "").String(),
 		Type:             parser.GetOpt("type", "mysql").String(),
 		Role:             "master",
diff --git a/database/gdb/gdb_z_mysql_internal_test.go b/database/gdb/gdb_z_mysql_internal_test.go
index 9909f2a82..f2ee66f43 100644
--- a/database/gdb/gdb_z_mysql_internal_test.go
+++ b/database/gdb/gdb_z_mysql_internal_test.go
@@ -40,7 +40,7 @@ func init() {
 		Port:             "3306",
 		User:             TestDbUser,
 		Pass:             TestDbPass,
-		Timezone:         "Asia/Shanghai",
+		Timezone:         "Asia/Shanghai", // For calculating UT cases of datetime zones in convenience.
 		Name:             parser.GetOpt("name", "").String(),
 		Type:             parser.GetOpt("type", "mysql").String(),
 		Role:             "master",