diff --git a/src/sql/optimizer/ob_optimizer_util.cpp b/src/sql/optimizer/ob_optimizer_util.cpp
index abef3f5589..bf8c270801 100644
--- a/src/sql/optimizer/ob_optimizer_util.cpp
+++ b/src/sql/optimizer/ob_optimizer_util.cpp
@@ -4764,6 +4764,17 @@ int ObOptimizerUtil::is_lossless_column_cast(const ObRawExpr* expr, bool& is_los
             is_lossless = true;
           }
         }
+      } else if (ObBitTC == column_tc) {
+        if (ObNumberTC == dst_tc) {
+          const double log10_2 = 0.30103;
+          ObAccuracy lossless_acc = column_type.get_accuracy();
+          if (dst_acc.get_scale() >= 0 &&
+              dst_acc.get_precision() - dst_acc.get_scale() >= lossless_acc.get_precision() * log10_2) {
+            // log10(2) = 0.30102999566398114; log10(2^n) = n*log10(2);
+            // cast(b'111' as decimal(1,0)) is lossless
+            is_lossless = true;
+          }
+        }
       } else if (ObFloatTC == column_tc || ObDoubleTC == column_tc) {
         if (ObDoubleTC == dst_tc) {
           if (-1 == dst_acc.get_precision() && -1 == dst_acc.get_scale()) {
diff --git a/src/sql/parser/sql_parser_mysql_mode.l b/src/sql/parser/sql_parser_mysql_mode.l
index d5fa599b63..01425634ab 100644
--- a/src/sql/parser/sql_parser_mysql_mode.l
+++ b/src/sql/parser/sql_parser_mysql_mode.l
@@ -1349,7 +1349,7 @@ BEGIN(in_c_comment);
     // for 'select -   -1 from dual'
     // the first neg sign is not copied when it is parsed
     // but when the second neg sign is parsed, the first neg sign must be put where is should be
-    if ('-' == yytext[0]) {
+    if ('-' == yytext[0] && IS_NEED_PARAMETERIZE) {
       REPUT_NEG_SIGN(p);
       p->minus_ctx_.pos_ = p->no_param_sql_len_;
       p->minus_ctx_.raw_sql_offset_ = yylloc->first_column - 1;
diff --git a/src/sql/resolver/dml/ob_dml_resolver.cpp b/src/sql/resolver/dml/ob_dml_resolver.cpp
index c02a54d457..19809a9aff 100644
--- a/src/sql/resolver/dml/ob_dml_resolver.cpp
+++ b/src/sql/resolver/dml/ob_dml_resolver.cpp
@@ -5329,8 +5329,8 @@ int ObDMLResolver::parse_qb_in_rewrite_hint(const ParseNode* hint_node, common::
       ret = OB_ERR_UNEXPECTED;
       LOG_WARN("qb table name has no one children.", K(ret));
     } else if (OB_ISNULL(qb_table_name->children_[0])) {
-      ret = OB_ERR_UNEXPECTED;
-      LOG_WARN("qb table name has null children.", K(ret));
+      // allowed use hint like USE_CONCAT()
+      type = hint_type;
     } else if (OB_FAIL(resolve_qb_name_node(qb_table_name->children_[0], qb_name))) {
       LOG_WARN("failed to resolve the rewrite hint.", K(ret));
     } else if (OB_FAIL(qb_names.push_back(qb_name))) {
diff --git a/src/sql/resolver/dml/ob_sql_hint.cpp b/src/sql/resolver/dml/ob_sql_hint.cpp
index 7935f7b726..57bea31f9e 100644
--- a/src/sql/resolver/dml/ob_sql_hint.cpp
+++ b/src/sql/resolver/dml/ob_sql_hint.cpp
@@ -1209,6 +1209,9 @@ int ObStmtHint::print_rewrite_hints_for_outline(planText& plan_text, const char*
     for (int64_t idx = 0; OB_SUCC(ret) && idx < qb_names.count(); ++idx) {
       ObString qb_name = qb_names.at(idx);
       if (OUTLINE_DATA == outline_type && OB_FAIL(query_ctx->get_stmt_org_name(qb_name, origin_name))) {
+        // for invalid qb name, reset ret
+        // select /*+use_concat(@sel$5)*/ * from t1;
+        ret = OB_SUCCESS;
       } else if (USED_HINT == outline_type && FALSE_IT(origin_name = qb_name)) {
       } else if (!is_oneline && OB_FAIL(BUF_PRINTF("\n"))) {
       } else if (OB_FAIL(BUF_PRINTF(get_outline_indent(is_oneline)))) {
diff --git a/src/sql/rewrite/ob_transform_join_elimination.cpp b/src/sql/rewrite/ob_transform_join_elimination.cpp
index 9b31cb732d..4de788b2fe 100644
--- a/src/sql/rewrite/ob_transform_join_elimination.cpp
+++ b/src/sql/rewrite/ob_transform_join_elimination.cpp
@@ -694,9 +694,6 @@ int ObTransformJoinElimination::eliminate_outer_join(ObDMLStmt* stmt, bool& tran
           LOG_WARN("semi info is null", K(ret));
         } else if (OB_FAIL(ObOptimizerUtil::remove_item(semi_infos.at(i)->left_table_ids_, table_ids))) {
           LOG_WARN("failed to eliminate outer join in from items.", K(ret));
-        } else if (OB_UNLIKELY(semi_infos.at(i)->left_table_ids_.empty())) {
-          ret = OB_ERR_UNEXPECTED;
-          LOG_WARN("left_table_ids_ is empty", K(ret));
         }
       }
       if (OB_FAIL(ret)) {
diff --git a/src/sql/rewrite/ob_transform_outerjoin_limit_pushdown.cpp b/src/sql/rewrite/ob_transform_outerjoin_limit_pushdown.cpp
index 44694d40a5..8fd3223dbd 100644
--- a/src/sql/rewrite/ob_transform_outerjoin_limit_pushdown.cpp
+++ b/src/sql/rewrite/ob_transform_outerjoin_limit_pushdown.cpp
@@ -452,7 +452,7 @@ int ObTransformOuterJoinLimitPushDown::do_transform(OjLimitPushDownHelper& helpe
                                         helper.view_table_,
                                         helper.extracted_conditions_,
                                         helper.saved_order_items_,
-                                        !helper.need_create_view_,
+                                        helper.need_rename_,
                                         helper.is_limit_only_))) {
     LOG_WARN("failed to push down view table", K(ret));
   } else { /* do nothing */