text: -- @testpoint: alter table 修改有空值的列为not null,合理报错
  drop table if exists table_alter_001;
  create table table_alter_001
  (
  c1 int,
  c2 bigint,
  c3 varchar(20)
  );
  insert into table_alter_001 values('11',null,'sss');
  insert into table_alter_001 values('21','','sss');
  insert into table_alter_001 values('31',66,'');
  insert into table_alter_001 values('41',66,null);
  
  alter table table_alter_001 modify c3 varchar(50);
  alter table table_alter_001 modify c3 not null;
  insert into table_alter_001 values('','','');
  alter table table_alter_001 modify c2 varchar(60);
  alter table table_alter_001 modify c1 varchar(60);
  drop table if exists table_alter_001;