comment

create table ctable_name
(
 
       field1 varchar2(20), --注释的内容1
       field2 number,       --注释的内容2
       field3 char(2),      --注释的内容3
       field4 date         
)
--select * from ctable_name;
comment on table ctable_name is '对表注释的内容';
select * from user_tab_comments where table_name = 'CTABLE_NAME';
 
comment on column ctable_name.field1 is '对field1列注释的内容';
select * from user_col_comments where table_name = 'CTABLE_NAME' 
and column_name = 'FIELD1';

 这个是对字段的注释，对表数据和表结构没有影响，

你可以在查看表和编辑界面看到他的注释

COMMENT ON TABLE T_KD_BACKUP_PARAM
  IS '数据归档参数表';
COMMENT ON COLUMN T_KD_BACKUP_PARAM.ID
  IS '序号';
COMMENT ON COLUMN T_KD_BACKUP_PARAM.PARAMNAME
  IS '参数名称';
COMMENT ON COLUMN T_KD_BACKUP_PARAM.PARAMVALUE
  IS '参数值';
COMMENT ON COLUMN T_KD_BACKUP_PARAM.PARAMPURPOSE
  IS '参数用途';