sqlserver数据库里怎么查找一个表里的约束，要查出 约束名、列名、约束类型？用sql语句查询

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)

主键约束（Primary Key constraint）：要求主键列数据唯一，并且不允许为空。

唯一约束（Unique constraint）：要求该列唯一，允许为空，但只能出现一个空值。

检查约束（Check constraint）：某列取值范围限制，格式限制等，如有关年龄、邮箱（必须有@）的约束。

默认约束（Default constraint）：某列的默认值，如在数据库里有一项数据很多重复，可以设为默认值。

外键约束（Foreign Key constraint）：用于在两个表之间建立关系，需要指定引用主表的哪一列。

扩展资料

主键约束在表中定义一个主键来唯一确定表中每一行数据的标识符。

（非空，唯一）

例如：

alter table member

add

constraint PK_member_member_no primary key clustered (member_no)

主键列的数据类型不限，但此列必须是唯一并且非空。

如该表中已有主键为1000的行，则不能再添加主键为1000。

人工或程序不好控制的时候，也可以设置主键列为自动增长列。

主键主要用在查询单调数据，修改单调数据和删除单调数据上。做程序的时候，都将表的主键设置为int型的可自增的列，这样在编程的时候，很容易区分数据。

参考资料来源：百度百科-主键约束

参考资料来源：百度百科-约束