修复视图的nullable数值不一致问题

src/observer/virtual_table/ob_information_columns_table.cpp

@@ -1061,9 +1061,7 @@ int ObInfoSchemaColumnsTable::fill_row_cells(const common::ObString &database_na
             break;
           }
         case IS_NULLABLE: {
-            ObString nullable_val = ObString::make_string(
-                column_attributes.null_ ? "YES" : "NO");
-            cells[cell_idx].set_varchar(nullable_val);
+            cells[cell_idx].set_varchar(column_attributes.null_);
             cells[cell_idx].set_collation_type(ObCharset::get_default_collation(
                                                    ObCharset::get_default_charset()));
             break;

src/sql/resolver/ddl/ob_create_view_resolver.cpp

@@ -1280,6 +1280,7 @@ int ObCreateViewResolver::fill_column_meta_infos(const ObRawExpr &expr,
   column.set_collation_type(expr.get_collation_type());
   column.set_accuracy(expr.get_accuracy());
   column.set_zero_fill(expr.get_result_type().has_result_flag(ZEROFILL_FLAG));
+  column.set_nullable(expr.get_result_type().is_not_null_for_read() ? false : true);
   if (OB_FAIL(ret)) {
   } else if (column.is_enum_or_set() && OB_FAIL(column.set_extended_type_info(expr.get_enum_set_values()))) {
     LOG_WARN("set enum or set info failed", K(ret), K(expr));