diff --git a/src/sql/resolver/ddl/ob_alter_table_resolver.cpp b/src/sql/resolver/ddl/ob_alter_table_resolver.cpp
index 0832144622..821ced1a1d 100644
--- a/src/sql/resolver/ddl/ob_alter_table_resolver.cpp
+++ b/src/sql/resolver/ddl/ob_alter_table_resolver.cpp
@@ -2017,8 +2017,14 @@ int ObAlterTableResolver::resolve_drop_index(const ParseNode &node)
                                                                true /* index table */,
                                                                index_table_schema))) {
             if (OB_TABLE_NOT_EXIST == ret) {
-              LOG_USER_ERROR(OB_TABLE_NOT_EXIST, to_cstring(alter_table_stmt->get_org_database_name()),
-                             to_cstring(alter_table_stmt->get_org_table_name()));
+              if (is_mysql_mode()) {
+                ret = OB_ERR_CANT_DROP_FIELD_OR_KEY;
+                LOG_WARN("index does not exist", K(ret), K(drop_index_name));
+                LOG_USER_ERROR(OB_ERR_CANT_DROP_FIELD_OR_KEY, drop_index_name.length(), drop_index_name.ptr());
+              } else {
+                LOG_USER_ERROR(OB_TABLE_NOT_EXIST, to_cstring(alter_table_stmt->get_org_database_name()),
+                              to_cstring(alter_table_stmt->get_org_table_name()));
+              }
             }
             LOG_WARN("fail to get index table schema", K(ret));
           } else if (OB_ISNULL(index_table_schema)) {
diff --git a/src/sql/resolver/expr/ob_raw_expr_util.cpp b/src/sql/resolver/expr/ob_raw_expr_util.cpp
index c41390b0d4..fd7338a6bd 100644
--- a/src/sql/resolver/expr/ob_raw_expr_util.cpp
+++ b/src/sql/resolver/expr/ob_raw_expr_util.cpp
@@ -1838,7 +1838,13 @@ int ObRawExprUtils::check_deterministic_single(const ObRawExpr *expr,
   int ret = OB_SUCCESS;
   CK (OB_NOT_NULL(expr));
   if (OB_SUCC(ret) && ObResolverUtils::DISABLE_CHECK != check_status) {
-    if (expr->is_sys_func_expr()) {
+    if (is_oracle_mode()
+        && (T_FUN_SYS_DEFAULT == expr->get_expr_type()
+           || T_OP_IS == expr->get_expr_type())) {
+      ret = OB_NOT_SUPPORTED;
+      LOG_USER_ERROR(OB_NOT_SUPPORTED, "Use special functions in generated columns");
+      LOG_WARN("special function is not suppored in generated column", K(ret), KPC(expr));
+    } else if (expr->is_sys_func_expr()) {
       bool is_non_pure_func = false;
       if (OB_FAIL(expr->is_non_pure_sys_func_expr(is_non_pure_func))) {
         LOG_WARN("check is non pure sys func expr failed", K(ret));