--使用在SQL2008,***查询字段说明和默认值select   object_name(c.id) as 表名   ,c.name as 字段名   ,t.name as 数据类型   ,c.prec as 长度   ,p.value as 字段说明   ,m.text as 默认值  from syscolumns c   inner join   systypes t   on c.xusertype=t.xusertype   left join  sys.extended_properties p   on c.id=p.major_id and c.colid = p.minor_id   left join   syscomments m   on c.cdefault=m.id-------------------------------------------------------------------------------------------select * from sys.extended_properties  --SQL2008 扩展属性表（字段注释，）----------------------------------------------------------------------------------------------------/*在sql2000中使用*/--获取所有默认值：select   object_name(c.id) as 表名   ,c.name as 字段名   ,t.name as 数据类型   ,c.prec as 长度   ,p.value as 字段说明   ,m.text as 默认值  from syscolumns c   inner join   systypes t   on c.xusertype=t.xusertype   left join    sysproperties p   on c.id=p.id and c.colid = p.smallid   left join   syscomments m   on c.cdefault=m.id--获取单个字段默认值：select   object_name(c.id) as 表名   ,c.name as 字段名   ,t.name as 数据类型   ,c.prec as 长度   ,p.value as 字段说明   ,m.text as 默认值  from syscolumns c   inner join   systypes t   on c.xusertype=t.xusertype   left join    sysproperties p   on c.id=p.id and c.colid = p.smallid   left join   syscomments m   on c.cdefault=m.id  where objectproperty(c.id,'IsUserTable')=1   and object_name(c.id) = '表名' and c.name = '字段名称'  -----------------------------------------------------------------------------------------------------查询指定表的指定字段的默认值select   object_name(c.id) as 表名   ,c.name as 字段名   ,t.name as 数据类型   ,c.prec as 长度   ,p.value as 字段说明   ,m.text as 默认值  from syscolumns c   inner join   systypes t   on c.xusertype=t.xusertype   left join  sys.extended_properties p   on c.id=p.major_id and c.colid = p.minor_id    left join   syscomments m   on c.cdefault=m.id  where objectproperty(c.id,'IsUserTable')=1   and object_name(c.id) = '表名' and c.name = '字段名'