SQL Server 查询表的主键的两种方式

方式一：

select b.column_name
from information_schema.table_constraints a
inner join information_schema.constraint_column_usage b
on a.constraint_name = b.constraint_name
where a.constraint_type = 'PRIMARY KEY' and a.table_name = 'products'
go

方式二：

SELECT a.name
  FROM   syscolumns a
  inner  join sysobjects d on a.id=d.id      
  where  d.name='products' and 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 
)))