重庆分公司,新征程启航

为企业提供网站建设、域名注册、服务器等服务

sqlserver约束,sqlserver约束类型

怎么查看sqlserver 中约束

主键约束

成都创新互联是一家专业提供陆良企业网站建设,专注与成都做网站、成都网站建设、H5响应式网站、小程序制作等业务。10年已为陆良众多企业、政府机构等服务。创新互联专业网站制作公司优惠进行中。

SELECT

tab.name AS [表名],

idx.name AS [主键名称],

col.name AS [主键列名]

FROM

sys.indexes idx

JOIN sys.index_columns idxCol

ON (idx.object_id = idxCol.object_id

AND idx.index_id = idxCol.index_id

AND idx.is_primary_key = 1)

JOIN sys.tables tab

ON (idx.object_id = tab.object_id)

JOIN sys.columns col

ON (idx.object_id = col.object_id

AND idxCol.column_id = col.column_id);

唯一约束

SELECT

tab.name AS [表名],

idx.name AS [约束名称],

col.name AS [约束列名]

FROM

sys.indexes idx

JOIN sys.index_columns idxCol

ON (idx.object_id = idxCol.object_id

AND idx.index_id = idxCol.index_id

AND idx.is_unique_constraint = 1)

JOIN sys.tables tab

ON (idx.object_id = tab.object_id)

JOIN sys.columns col

ON (idx.object_id = col.object_id

AND idxCol.column_id = col.column_id);

外键约束

select

oSub.name AS [子表名称],

fk.name AS [外键名称],

SubCol.name AS [子表列名],

oMain.name AS [主表名称],

MainCol.name AS [主表列名]

from

sys.foreign_keys fk

JOIN sys.all_objects oSub

ON (fk.parent_object_id = oSub.object_id)

JOIN sys.all_objects oMain

ON (fk.referenced_object_id = oMain.object_id)

JOIN sys.foreign_key_columns fkCols

ON (fk.object_id = fkCols.constraint_object_id)

JOIN sys.columns SubCol

ON (oSub.object_id = SubCol.object_id

AND fkCols.parent_column_id = SubCol.column_id)

JOIN sys.columns MainCol

ON (oMain.object_id = MainCol.object_id

AND fkCols.referenced_column_id = MainCol.column_id)

Check约束

SELECT

tab.name AS [表名],

chk.name AS [Check约束名],

col.name AS [列名],

chk.definition

FROM

sys.check_constraints chk

JOIN sys.tables tab

ON (chk.parent_object_id = tab.object_id)

JOIN sys.columns col

ON (chk.parent_object_id = col.object_id

AND chk.parent_column_id = col.column_id)

sqlserver 5种约束表示什么意思

在SQLServer中,有3种不同类型的约束。

1、实体约束

实体约束是关于行的,比如某一行出现的值就不允许出现在其他行,例如主键。

2、域约束

域约束是关于列的,对于所有行,某一列有那些约束,例如CHECK约束。

3、参照完整性约束

如果某列的值必须与其他列的值匹配,那就意味着需要一个参照完整性约束,例如外键。

SQLServer中的check约束

ALTER TABLE NewTable

ADD CONSTRAINT CK_NewId CHECK(NewId in[0,1])

ADD CONSTRAINT CK_endtime CHECK(begintimeendtime)

(NewTable 为您的表,NewId为该表中的某个字段)

提示:您endtime应该作为--下机时间 begintime应该作为--上机时间 ;这样更符合逻辑,由于您给出的题目,所以答题如上,如果 是您笔误,那么 第二条约束改为 ..(endtimebegintime)即可。。


网页标题:sqlserver约束,sqlserver约束类型
新闻来源:http://cqcxhl.cn/article/dsephig.html

其他资讯

在线咨询
服务热线
服务热线:028-86922220
TOP