fix incorrect collation level bug when building null expr

src/sql/rewrite/ob_transform_join_elimination.cpp

@@ -1090,12 +1090,19 @@ int ObTransformJoinElimination::do_eliminate_left_outer_join(ObDMLStmt *stmt,
                                                              0,    /* result_flag */
                                                              ctx_->session_info_, cm))) {
           LOG_WARN("fail to get default cast mode", K(ret));
-        } else if (OB_FAIL(ObRawExprUtils::create_cast_expr(*ctx_->expr_factory_, 
+        } else if (is_mysql_mode() &&
+                   OB_FAIL(ObRawExprUtils::create_cast_expr(*ctx_->expr_factory_, 
                                                             to_expr, 
                                                             from_expr->get_result_type(), 
                                                             cast_expr, ctx_->session_info_,
                                                             false, cm))) {
           LOG_WARN("failed to cast expr", K(ret), K(*from_expr), K(*to_expr));
+        } else if (is_oracle_mode() &&
+                   OB_FAIL(ObRawExprUtils::create_cast_expr(*ctx_->expr_factory_, 
+                                                            to_expr, 
+                                                            from_expr->get_result_type(), 
+                                                            cast_expr, ctx_->session_info_))) {
+          LOG_WARN("failed to cast expr", K(ret), K(*from_expr), K(*to_expr));
         } else if (OB_ISNULL(cast_expr)) {
           ret = OB_ERR_UNEXPECTED;
           LOG_WARN("get unexpected null expr", K(ret));

src/sql/rewrite/ob_transform_left_join_to_anti.cpp

@@ -295,6 +295,7 @@ int ObTransformLeftJoinToAnti::trans_stmt_to_anti(ObDMLStmt *stmt, const JoinedT
       ObRawExpr *from_expr = NULL;
       ObRawExpr *to_expr = NULL;
       ObSysFunRawExpr *cast_expr = NULL;
+      ObCastMode cm;
       if (OB_ISNULL(col_item = stmt->get_column_item(i)) ||
           OB_ISNULL(from_expr = col_item->expr_)) {
         ret = OB_ERR_UNEXPECTED;
@@ -304,12 +305,23 @@ int ObTransformLeftJoinToAnti::trans_stmt_to_anti(ObDMLStmt *stmt, const JoinedT
       } else if (OB_FAIL(ObRawExprUtils::build_null_expr(*ctx_->expr_factory_,
                                                          to_expr))) {
         LOG_WARN("failed to build null expr", K(ret));
-      } else if (OB_FAIL(ObRawExprUtils::create_cast_expr(*ctx_->expr_factory_,
-                                                          to_expr,
-                                                          from_expr->get_result_type(),
-                                                          cast_expr,
-                                                          ctx_->session_info_))) {
-        LOG_WARN("failed to create cast expr", K(ret));
+      } else if (OB_FAIL(ObSQLUtils::get_default_cast_mode(true,/* explicit_cast */
+                                                            0,    /* result_flag */
+                                                            ctx_->session_info_, cm))) {
+        LOG_WARN("fail to get default cast mode", K(ret));
+      } else if (is_mysql_mode() &&
+                  OB_FAIL(ObRawExprUtils::create_cast_expr(*ctx_->expr_factory_, 
+                                                            to_expr, 
+                                                            from_expr->get_result_type(), 
+                                                            cast_expr, ctx_->session_info_,
+                                                            false, cm))) {
+          LOG_WARN("failed to cast expr", K(ret), K(*from_expr), K(*to_expr));
+        } else if (is_oracle_mode() &&
+                   OB_FAIL(ObRawExprUtils::create_cast_expr(*ctx_->expr_factory_, 
+                                                            to_expr, 
+                                                            from_expr->get_result_type(), 
+                                                            cast_expr, ctx_->session_info_))) {
+          LOG_WARN("failed to cast expr", K(ret), K(*from_expr), K(*to_expr));
       } else if (OB_ISNULL(to_expr = cast_expr)) {
         ret = OB_ERR_UNEXPECTED;
         LOG_WARN("get unexpected null cast expr", K(ret));