从SQL Server语句确定主键

Question

鉴于以下T-SQL语句，我（通过检查）如何确定主键？如果它没有列出（像我怀疑）它会是什么样子？

CREATE TABLE [dbo].[BLDGINFO](
    [LBLDGRUNNO] [int] NULL, 
    [LBLDGNO] [int] NOT NULL, 
    [FBIVOLUME] [float] NULL, 
    [FBIACOND] [float] NULL, 
    [NBIHTYPE] [float] NULL, 
    [NBILTYPE] [float] NULL, 
    [NBISTORIES] [float] NULL, 
    [NBIFTYPE] [float] NULL, 
    [NBIBEDS] [float] NULL, 
    [NBIUNITS] [float] NULL, 
    [SBIRATENO] [nvarchar](31) NULL, 
    [NBICTYPE] [float] NULL, 
    [NBIYEARBLT] [int] NULL DEFAULT ((0)), 
    [NBITHBNDRY] [int] NULL 
) ON [PRIMARY] 

Answer 1

如果主键已经定义完毕，将会是LBLDGNO。但是，很可能根本没有定义主键。您可以如下确定：

SELECT c.name 
FROM sys.indexes i, sys.index_columns ic, sys.objects o, sys.columns c 
WHERE o.object_id = i.object_id 
AND ic.index_id = i.index_id AND ic.object_id = i.object_id 
AND c.object_id = o.object_id AND c.column_id = ic.column_id 
AND i.is_primary_key = 1 
AND o.name = 'BLDGINFO' 

此查询将返回包含在主键中的所有列。如果它返回一个空的结果集，那么没有定义主键。

Answer 2

在你的问题表定义不包含主键，这里是被定义为ID列主键为例：

CREATE TABLE [dbo].[BLDGINFO](
    id int NOT NULL, 
    [LBLDGRUNNO] [int] NULL, 
    [LBLDGNO] [int] NOT NULL, 
    [FBIVOLUME] [float] NULL, 
    [FBIACOND] [float] NULL, 
    [NBIHTYPE] [float] NULL, 
    [NBILTYPE] [float] NULL, 
    [NBISTORIES] [float] NULL, 
    [NBIFTYPE] [float] NULL, 
    [NBIBEDS] [float] NULL, 
    [NBIUNITS] [float] NULL, 
    [SBIRATENO] [nvarchar](31) NULL, 
    [NBICTYPE] [float] NULL, 
    [NBIYEARBLT] [int] NULL DEFAULT ((0)), 
    [NBITHBNDRY] [int] NULL, 
    PRIMARY KEY (id) 
) ON [PRIMARY] 

Answer 3

表格中的唯一字段可能可以工作作为主键是LBLDGNO，因为主键列不能为空。