fix -- 优化sql脚本，添加默认值

script/sql/oracle/update/update_v0.4.4~v0.5.0.sql

@@ -16,7 +16,7 @@ create table wf_copy (
    create_time     date,
    update_by       varchar(64)    default '',
    update_time     date,
-   del_flag        nchar(1)
+   del_flag        nchar(1)       default '0'
 );
 
 alter table wf_copy add constraint pk_wf_copy primary key (copy_id);