diff --git a/src/sql/code_generator/ob_dml_cg_service.cpp b/src/sql/code_generator/ob_dml_cg_service.cpp
index 06e7fd4a80..759d69acdf 100644
--- a/src/sql/code_generator/ob_dml_cg_service.cpp
+++ b/src/sql/code_generator/ob_dml_cg_service.cpp
@@ -2016,12 +2016,31 @@ int ObDmlCgService::convert_normal_triggers(ObLogDelUpd &log_op,
           LOG_DEBUG("debug trigger normal column", K(ret), K(is_instead_of),
               K(dml_ctdef.old_row_.count()), K(dml_ctdef.new_row_.count()));
           if (ObTriggerEvents::is_insert_event(dml_event)) {
-            new_expr = dml_ctdef.new_row_.at(col_idx);
+            if (OB_UNLIKELY(col_idx < 0) ||
+                OB_UNLIKELY(col_idx >= dml_ctdef.new_row_.count())) {
+              ret = OB_ERR_UNEXPECTED;
+              LOG_WARN("unexpected col idx", K(col_idx), K(dml_ctdef.new_row_));
+            } else {
+              new_expr = dml_ctdef.new_row_.at(col_idx);
+            }
           } else if (ObTriggerEvents::is_update_event(dml_event)) {
-            new_expr = dml_ctdef.new_row_.at(col_idx);
-            old_expr = dml_ctdef.old_row_.at(col_idx);
+            if (OB_UNLIKELY(col_idx < 0) ||
+                OB_UNLIKELY(col_idx >= dml_ctdef.new_row_.count()) ||
+                OB_UNLIKELY(col_idx >= dml_ctdef.old_row_.count())) {
+              ret = OB_ERR_UNEXPECTED;
+              LOG_WARN("unexpected col idx", K(col_idx), K(dml_ctdef.new_row_), K(dml_ctdef.old_row_));
+            } else {
+              new_expr = dml_ctdef.new_row_.at(col_idx);
+              old_expr = dml_ctdef.old_row_.at(col_idx);
+            }
           } else if (ObTriggerEvents::is_delete_event(dml_event)) {
-            old_expr = dml_ctdef.old_row_.at(col_idx);
+            if (OB_UNLIKELY(col_idx < 0) ||
+                OB_UNLIKELY(col_idx >= dml_ctdef.old_row_.count())) {
+              ret = OB_ERR_UNEXPECTED;
+              LOG_WARN("unexpected col idx", K(col_idx), K(dml_ctdef.old_row_));
+            } else {
+              old_expr = dml_ctdef.old_row_.at(col_idx);
+            }
           } else {
             ret = OB_ERR_UNEXPECTED;
             LOG_WARN("unexpected status: not supported dml type",
diff --git a/src/sql/rewrite/ob_transform_rule.cpp b/src/sql/rewrite/ob_transform_rule.cpp
index 35de111bee..8222962829 100644
--- a/src/sql/rewrite/ob_transform_rule.cpp
+++ b/src/sql/rewrite/ob_transform_rule.cpp
@@ -624,6 +624,9 @@ int ObTransformRule::need_transform(const common::ObIArray<ObParentDMLStmt> &par
   if (is_normal_disabled_transform(stmt)) {
     need_trans = false;
     OPT_TRACE("hierarchical query or insert query can not transform");
+  } else if (stmt.has_instead_of_trigger()) {
+    need_trans = false;
+    OPT_TRACE("stmt with instead of trigger can not transform");
   } else if (OB_FAIL(check_hint_status(stmt, need_trans))) {
     LOG_WARN("failed to check hint status", K(ret));
   }