text: -- @testpoint: 添加主键约束约束后修改列
  
  drop table if exists test_modify cascade;
  create table test_modify(
  c_id int,
  c_integer integer,
  c_real real,
  c_float float,
  c_cdouble binary_double,
  c_decimal decimal(38),
  c_number number(38),
  c_number1 number,
  c_number2 number(20,10),
  c_numeric numeric(38),
  c_char char(50) default null,
  c_varchar varchar(20),
  c_varchar2 varchar2(4000),
  c_clob clob,
  c_raw raw(20),
  c_blob blob,
  c_date date,
  c_timestamp timestamp
  );
  
  alter table test_modify add  CONSTRAINT cc PRIMARY KEY (c_id);
  alter table test_modify MODIFY (c_id char(20));
  
  SELECT col_description(a.attrelid,a.attnum) as comment,format_type(a.atttypid,a.atttypmod) as type,a.attname as name, a.attnotnull as notnull
  FROM pg_class as c,pg_attribute as a
  where c.relname = 'test_modify' and a.attrelid = c.oid and a.attnum>0;
  
  drop table if exists test_modify cascade;
  