text: -- @testpoint: 聚集函数var_samp，入参为字符串，合理报错
  
  drop table if exists t_nvl_rca_tab;
  create table t_nvl_rca_tab(col_1 varchar);
  insert into t_nvl_rca_tab values ('sqlll');
  insert into t_nvl_rca_tab values ('pythonnnn');
  select var_samp(col_1) from t_nvl_rca_tab;
  drop table if exists t_nvl_rca_tab;