text: -- @testpoint:explain plan语句结合exist子查询使用
  -- @modify at: 2020-11-12
  --建表
  drop table if exists explain_t1;
  drop table if exists explain_t2;
  create table explain_t1(a int, b int);
  create table explain_t2(f1 int,f2 int);
  --使用explain plan语句，返回EXPLAIN SUCCESS
  explain plan for select a from explain_t1 where a not in (select f1 from explain_t2);
  --查询PLAN_TABLE表信息,statement_id字段为空
  select statement_id,object_name,options from PLAN_TABLE where object_name in('explain_t1','explain_t2');
  --清理PLAN_TABLE表信息
  delete from PLAN_TABLE;
  --删表
  drop table explain_t1;
  drop table explain_t2;
  