MySQL:
select table_name 表名,table_comment 注释
from information_schema.tables
where table_schema = '数据库名'
MsSQL:
select c.name as 表名,a.value as 注释
from sys.extended_properties a
join (
select distinct id
from syscolumns
)b on a.major_id=b.id
join sysobjects c on b.id=c.id
where a.minor_id=0