表增加注释
comment on table 表名 is '表注释";
列增加注释
comment on column 表.列 is '列注释';
读取表注释
select * from user_tab_comments where comments is not NULL AND TABLE_NAME = '表名';
读取列注释 <可能不存在表 user_col_commnents >
select * from user_col_commnents where comments is not null and table_name='表名';