1:利用SQL自带的存储过程

EXEC sp_pkeys @table_name=''''表名''''

2:利用系统表INFORMATION_SCHEMA.KEY_COLUMN_USAGE

SELECT TABLE_NAME,COLUMN_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE TABLE_NAME=''''表名''''

3: 以下这个查询表结构的语句可能大家都见过：

利用syscolumns,sysindexes,sysindexkeys三个表关联可以查出主键

SELECT
 (case when a.colorder=1 then d.name else '''''''' end) N''''表名'''',
 a.colorder N''''字段序号'''',
 a.name N''''字段名'''',
 (case when COLUMNPROPERTY( a.id,a.name,''''IsIdentity'''')=1 then ''''√''''else '''''''' end) N''''标识'''',
 (case when (SELECT count(*)
 FROM sysobjects
 WHERE (name in
           (SELECT name
          FROM sysindexes
          WHERE (id = a.id) AND (indid in
                    (SELECT indid
                   FROM sysindexkeys
                   WHERE (id = a.id) AND (colid in
                             (SELECT colid
                            FROM syscolumns
                            WHERE (id = a.id) AND (name = a.name))))))) AND
        (xtype = ''''PK''''))>0 then ''''√'''' else '''''''' end) N''''主键'''',
 b.name N''''类型'''',
 a.length N''''占用字节数'''',
 COLUMNPROPERTY(a.id,a.name,''''PRECISION'''') as N''''长度'''',
 isnull(COLUMNPROPERTY(a.id,a.name,''''Scale''''),0) as N''''小数位数'''',
 (case when a.isnullable=1 then ''''√''''else '''''''' end) N''''允许空'''',
 isnull(e.text,'''''''') N''''默认值'''',
 isnull(g.[value],'''''''') AS N''''字段说明''''
--into ##tx

FROM  syscolumns  a left join systypes b
on  a.xtype=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 
order by object_name(a.id),a.colorder

4:

select o.name as 表名,c.name as 字段名,k.colid as 字段序号,k.keyno as 索引顺序 from sysindexes i
join sysindexkeys k on i.id = k.id and i.indid = k.indid
join sysobjects o on i.id = o.id
join syscolumns c on i.id=c.id and k.colid = c.colid
where o.xtype = ''''U''''
and exists(select 1 from sysobjects where xtype = ''''PK'''' and name = i.name)
order by o.name,k.colid