從SQL Server語句確定主鍵

Question

鑑於以下T-SQL語句，我（通過檢查）如何確定主鍵？如果它沒有列出（像我懷疑）它會是什麼樣子？

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

如果主鍵已經定義完畢，將會是LBLDGNO。但是，很可能根本沒有定義主鍵。您可以如下確定：

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' 

此查詢將返回包含在主鍵中的所有列。如果它返回一個空的結果集，那麼沒有定義主鍵。

Answer 2

在你的問題表定義不包含主鍵，這裏是被定義爲ID列主鍵爲例：

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爲主鍵是LBLDGNO，因爲主鍵列不能爲空。