-- 1。 从数据库中读出该库中的所有表名
select name from [DBAP].dbo.sysobjects where xtype='U'

-- 2。 怎样可以读出表和字段的说明，怎样设置说明
select a.name 'tablename',b.name 'colname',c.value
from sys.objects a
inner join sys.columns b on a.object_id=b.object_id
left join sys.extended_properties c 
on b.object_id=c.major_id and b.column_id=c.minor_id
where a.[type]='U'

------解决方案--------------------
SQL code
--sql server 2000
SELECT 
    表名       = case when a.colorder=1 then d.name else '' end,
    表说明     = case when a.colorder=1 then isnull(f.value,'') else '' end,
    字段序号   = a.colorder,
    字段名     = a.name,
    标识       = case when COLUMNPROPERTY( a.id,a.name,'IsIdentity')=1 then '√'else '' end,
    主键       = case when exists(SELECT 1 FROM sysobjects where xtype='PK' and parent_obj=a.id and name in (
                     SELECT name FROM sysindexes WHERE indid in(
                        SELECT indid FROM sysindexkeys WHERE id = a.id AND colid=a.colid))) then '√' else '' end,
    类型       = b.name,
    占用字节数 = a.length,
    长度       = COLUMNPROPERTY(a.id,a.name,'PRECISION'),
    小数位数   = isnull(COLUMNPROPERTY(a.id,a.name,'Scale'),0),
    允许空     = case when a.isnullable=1 then '√'else '' end,
    默认值     = isnull(e.text,''),
    字段说明   = isnull(g.[value],'')
FROM 
    syscolumns a
left join 
    systypes b 
on 
    a.xusertype=b.xusertype
inner join 
    sysobjects d 
on 
    a.id=d.id  and d.xtype='U' and  d.name<>'dtproperties'
left join 
    syscomments e 
on 
    a.cdefault=e.id
left join 
    sysproperties g 
on 
    a.id=g.id and a.colid=g.smallid  
left join 
    sysproperties f 
on 
    d.id=f.id and f.smallid=0
where 
    d.name='要查询的表'    --如果只查询指定表,加上此条件
order by 
    a.id,a.colorder



--sql server 2005
-- 1. 表结构信息查询 
-- ========================================================================
-- 表结构信息查询
-- 邹建 2005.08(引用请保留此信息)
-- ========================================================================
SELECT 
    TableName=CASE WHEN C.column_id=1 THEN O.name ELSE N'' END,
    TableDesc=ISNULL(CASE WHEN C.column_id=1 THEN PTB.[value] END,N''),
    Column_id=C.column_id,
    ColumnName=C.name,
    PrimaryKey=ISNULL(IDX.PrimaryKey,N''),
    [IDENTITY]=CASE WHEN C.is_identity=1 THEN N'√'ELSE N'' END,
    Computed=CASE WHEN C.is_computed=1 THEN N'√'ELSE N'' END,
    Type=T.name,
    Length=C.max_length,
    Precision=C.precision,
    Scale=C.scale,
    NullAble=CASE WHEN C.is_nullable=1 THEN N'√'ELSE N'' END,
    [Default]=ISNULL(D.definition,N''),
    ColumnDesc=ISNULL(PFD.[value],N''),
    IndexName=ISNULL(IDX.IndexName,N''),
    IndexSort=ISNULL(IDX.Sort,N''),
    Create_Date=O.Create_Date,
    Modify_Date=O.Modify_date
FROM sys.columns C
    INNER JOIN sys.objects O
        ON C.[object_id]=O.[object_id]
            AND O.type='U'
            AND O.is_ms_shipped=0
    INNER JOIN sys.types T
        ON C.user_type_id=T.user_type_id
    LEFT JOIN sys.default_constraints D
        ON C.[object_id]=D.parent_object_id
            AND C.column_id=D.parent_column_id
            AND C.default_object_id=D.[object_id]
    LEFT JOIN sys.extended_properties PFD
        ON PFD.class=1 
            AND C.[object_id]=PFD.major_id 
            AND C.column_id=PFD.minor_id
--             AND PFD.name='Caption'  -- 字段说明对应的描述名称(一个字段可以添加多个不同name的描述)
    LEFT JOIN sys.extended_properties PTB
        ON PTB.class=1 
            AND PTB.minor_id=0 
            AND C.[object_id]=PTB.major_id
--             AND PFD.name='Caption'  -- 表说明对应的描述名称(一个表可以添加多个不同name的描述) 
    LEFT JOIN                       -- 索引及主键信息
    (
        SELECT 
            IDXC.[object_id],
            IDXC.column_id,
            Sort=CASE INDEXKEY_PROPERTY(IDXC.[object_id],IDXC.index_id,IDXC.index_column_id,'IsDescending')
                WHEN 1 THEN