diff --git a/src/sql/printer/ob_select_stmt_printer.cpp b/src/sql/printer/ob_select_stmt_printer.cpp
index b94845b91f..4cf09df465 100644
--- a/src/sql/printer/ob_select_stmt_printer.cpp
+++ b/src/sql/printer/ob_select_stmt_printer.cpp
@@ -59,7 +59,7 @@ int ObSelectStmtPrinter::do_print()
           LOG_WARN("fail to print_unpivot",
                    KPC(stmt_->get_transpose_item()), K(ret));
         }
-      } else if (OB_FAIL(print())) {
+      } else if (OB_FAIL(SMART_CALL(print()))) {
         LOG_WARN("fail to print stmt", KPC(stmt_), K(ret));
       }
     }
diff --git a/src/sql/resolver/dml/ob_dml_stmt.cpp b/src/sql/resolver/dml/ob_dml_stmt.cpp
index 4a4d836da2..d7aa70b06f 100644
--- a/src/sql/resolver/dml/ob_dml_stmt.cpp
+++ b/src/sql/resolver/dml/ob_dml_stmt.cpp
@@ -4538,7 +4538,7 @@ int ObDMLStmt::disable_writing_external_table(bool basic_stmt_is_dml /* defualt
       } else if (schema::EXTERNAL_TABLE == table_item->table_type_) {
         disable_write_table = true;
       } else if (table_item->is_view_table_ && NULL != table_item->ref_query_) {
-        OZ( table_item->ref_query_->disable_writing_external_table(true) );
+        OZ( SMART_CALL(table_item->ref_query_->disable_writing_external_table(true)) );
       }
     }
   }
@@ -4551,7 +4551,7 @@ int ObDMLStmt::disable_writing_external_table(bool basic_stmt_is_dml /* defualt
       LOG_WARN("failed to get stmt's child_stmts", K(ret));
     } else {
       for (int64_t i = 0; OB_SUCC(ret) && i < child_stmts.count(); ++i) {
-        OZ( child_stmts.at(i)->disable_writing_external_table() );
+        OZ( SMART_CALL(child_stmts.at(i)->disable_writing_external_table()) );
       }
     }
   }
diff --git a/src/sql/resolver/expr/ob_raw_expr.cpp b/src/sql/resolver/expr/ob_raw_expr.cpp
index edd7addf5d..bc0999de0e 100644
--- a/src/sql/resolver/expr/ob_raw_expr.cpp
+++ b/src/sql/resolver/expr/ob_raw_expr.cpp
@@ -1609,7 +1609,9 @@ bool ObQueryRefRawExpr::inner_same_as(
   bool bool_ret = false;
   if (get_expr_type() == expr.get_expr_type()) {
     const ObQueryRefRawExpr &u_expr = static_cast<const ObQueryRefRawExpr &>(expr);
-    if (check_context != NULL && check_context->override_query_compare_) {
+    if (is_set_ != u_expr.is_set_ || is_multiset_ != u_expr.is_multiset_) {
+      /* bool bool_ret = false; */
+    } else if (check_context != NULL && check_context->override_query_compare_) {
       bool_ret = check_context->compare_query(*this, u_expr);
     } else {
       // very tricky, check the definition of ref_stmt_ and get_ref_stmt()
@@ -2356,6 +2358,27 @@ void ObOpRawExpr::clear_child()
   exprs_.reset();
 }
 
+int ObOpRawExpr::get_subquery_comparison_flag() const
+{
+  enum {
+    INVALID = 0, // not subquery comparison
+    NONE = 1,
+    ALL = 2,
+    ANY = 3
+  } comparison_flag;
+  comparison_flag = INVALID;
+  if (IS_SUBQUERY_COMPARISON_OP(get_expr_type())) {
+    if (has_flag(IS_WITH_ALL)) {
+      comparison_flag = ALL;
+    } else if (has_flag(IS_WITH_ANY)) {
+      comparison_flag = ANY;
+    } else {
+      comparison_flag = NONE;
+    }
+  }
+  return comparison_flag;
+}
+
 bool ObOpRawExpr::inner_same_as(
     const ObRawExpr &expr,
     ObExprEqualCheckContext *check_context) const
@@ -2393,6 +2416,12 @@ bool ObOpRawExpr::inner_same_as(
     } else {
       need_cmp = false;
     }
+  } else if (IS_SUBQUERY_COMPARISON_OP(get_expr_type())) {
+    const ObOpRawExpr &tmp = static_cast<const ObOpRawExpr &>(expr);
+    if (tmp.get_expr_type() != get_expr_type() ||
+        tmp.get_subquery_comparison_flag() != get_subquery_comparison_flag()) {
+      need_cmp = false;
+    }
   } else if (expr.get_expr_type() != get_expr_type()) {
     need_cmp = false;
   }
diff --git a/src/sql/resolver/expr/ob_raw_expr.h b/src/sql/resolver/expr/ob_raw_expr.h
index a215efb3ad..0869a408a6 100644
--- a/src/sql/resolver/expr/ob_raw_expr.h
+++ b/src/sql/resolver/expr/ob_raw_expr.h
@@ -2958,6 +2958,7 @@ public:
                                    int64_t &pos,
                                    ExplainType type) const;
   bool is_white_runtime_filter_expr() const override;
+  int get_subquery_comparison_flag() const;
   VIRTUAL_TO_STRING_KV_CHECK_STACK_OVERFLOW(N_ITEM_TYPE, type_,
                                             N_RESULT_TYPE, result_type_,
                                             N_EXPR_INFO, info_,
diff --git a/src/sql/rewrite/ob_transform_simplify_expr.cpp b/src/sql/rewrite/ob_transform_simplify_expr.cpp
index 53bef87aa7..c7cb98393e 100644
--- a/src/sql/rewrite/ob_transform_simplify_expr.cpp
+++ b/src/sql/rewrite/ob_transform_simplify_expr.cpp
@@ -2856,10 +2856,14 @@ int ObTransformSimplifyExpr::remove_duplicate_exprs(ObQueryCtx* query_ctx,
       LOG_WARN("failed to do remove duplicate exprs", K(ret));
     } else if (param_conds.count() == conditions.count()) {
       //do nothing
-    } else if (OB_FAIL(conditions.assign(param_conds))) {
-      LOG_WARN("assign array failed", K(ret));
     } else {
-      trans_happened = true;
+      OPT_TRACE("before remove duplicate exprs", conditions);
+      OPT_TRACE("after duplicate exprs happened", param_conds);
+      if (OB_FAIL(conditions.assign(param_conds))) {
+        LOG_WARN("assign array failed", K(ret));
+      } else {
+        trans_happened = true;
+      }
     }
   }
   if (OB_SUCC(ret) && trans_happened) {
@@ -2929,8 +2933,15 @@ int ObTransformSimplifyExpr::do_remove_duplicate_exprs(ObQueryCtx &query_ctx,
     ObStmtCompareContext cmp_ctx;
     cmp_ctx.init(&query_ctx.calculable_items_);
     for (int64_t i = param_count - 1; OB_SUCC(ret) && i >= 1; i--) {
+      if (OB_ISNULL(exprs.at(i))) {
+        ret = OB_ERR_UNEXPECTED;
+        LOG_WARN("unexpect null pointer error");
+      }
       for (int64_t j = 0; OB_SUCC(ret) && j < i; j++) {
-        if (exprs.at(i)->same_as(*exprs.at(j), &cmp_ctx)) {
+        if (OB_ISNULL(exprs.at(j))) {
+          ret = OB_ERR_UNEXPECTED;
+          LOG_WARN("unexpect null pointer error");
+        } else if (exprs.at(i)->same_as(*exprs.at(j), &cmp_ctx)) {
           if (OB_FAIL(exprs.remove(i))) {
             LOG_WARN("failed to remove", K(ret));
           } else if (!cmp_ctx.equal_param_info_.empty()) {