您可以使用这些查询为您的表查找所有fk。

Declare @SchemaName VarChar(200) = 'Schema Name'
Declare @TableName VarChar(200) = 'Table name'

-- Find FK in This table.
SELECT 
    'IF  EXISTS (SELECT * FROM sys.foreign_keys WHERE object_id = OBJECT_ID(N''' + 
      '[' + OBJECT_SCHEMA_NAME(FK.parent_object_id) + '].[' + FK.name + ']' 
      + ''') AND parent_object_id = OBJECT_ID(N''' + 
      '[' + OBJECT_SCHEMA_NAME(FK.parent_object_id) + '].[' 
      + OBJECT_NAME(FK.parent_object_id) + ']' + ''')) ' +

    'ALTER TABLE ' +  OBJECT_SCHEMA_NAME(FK.parent_object_id) +
    '.[' + OBJECT_NAME(FK.parent_object_id) + 
    '] DROP CONSTRAINT ' + FK.name
    , S.name , O.name, OBJECT_NAME(FK.parent_object_id)
FROM sys.foreign_keys AS FK
INNER JOIN Sys.objects As O 
  ON (O.object_id = FK.parent_object_id )
INNER JOIN SYS.schemas AS S 
  ON (O.schema_id = S.schema_id)  
WHERE 
      O.name = @TableName
      And S.name = @SchemaName


-- Find the FKs in the tables in which this table is used
  SELECT 
    ' IF  EXISTS (SELECT * FROM sys.foreign_keys WHERE object_id = OBJECT_ID(N''' + 
      '[' + OBJECT_SCHEMA_NAME(FK.parent_object_id) + '].[' + FK.name + ']' 
      + ''') AND parent_object_id = OBJECT_ID(N''' + 
      '[' + OBJECT_SCHEMA_NAME(FK.parent_object_id) + '].[' 
      + OBJECT_NAME(FK.parent_object_id) + ']' + ''')) ' +

    ' ALTER TABLE ' +  OBJECT_SCHEMA_NAME(FK.parent_object_id) +
    '.[' + OBJECT_NAME(FK.parent_object_id) + 
    '] DROP CONSTRAINT ' + FK.name
    , S.name , O.name, OBJECT_NAME(FK.parent_object_id)
FROM sys.foreign_keys AS FK
INNER JOIN Sys.objects As O 
  ON (O.object_id = FK.referenced_object_id )
INNER JOIN SYS.schemas AS S 
  ON (O.schema_id = S.schema_id)  
WHERE 
      O.name = @TableName
      And S.name = @SchemaName 

好吧，我知道我迟到了，但是下面是我认为最好的语法。如果需要，向OBJECT_ID子句添加模式名。

IF OBJECTPROPERTY(OBJECT_ID(N'My_FK_name'),'IsConstraint') =1
ALTER TABLE dbo.TableName DROP CONSTRAINT My_FK_name

Declare @FKeyRemoveQuery NVarchar(max)

IF EXISTS(SELECT 1 FROM sys.foreign_keys WHERE parent_object_id = OBJECT_ID(N'dbo.TableName'))

BEGIN
    SELECT @FKeyRemoveQuery='ALTER TABLE dbo.TableName DROP CONSTRAINT [' + LTRIM(RTRIM([name])) + ']'   
    FROM sys.foreign_keys
    WHERE parent_object_id = OBJECT_ID(N'dbo.TableName')

    EXECUTE Sp_executesql @FKeyRemoveQuery 

END

所有表约束都存储在INFORMATION_SCHEMA中。TABLE_CONSTRAINTS

IF EXISTS(SELECT * FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS AS C WHERE C.CONSTRAINT_NAME = '<CONSTRAINT NAME>' AND C.TABLE_NAME = '<TABLE NAME>')
BEGIN
    ALTER TABLE <TABLE NAME>
        DROP CONSTRAINT <CONSTRAINT NAME>
END
GO

我想这会对你有帮助……

    DECLARE @ConstraintName nvarchar(200)
SELECT 
    @ConstraintName = KCU.CONSTRAINT_NAME
FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS AS RC 
INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS KCU
    ON KCU.CONSTRAINT_CATALOG = RC.CONSTRAINT_CATALOG  
    AND KCU.CONSTRAINT_SCHEMA = RC.CONSTRAINT_SCHEMA 
    AND KCU.CONSTRAINT_NAME = RC.CONSTRAINT_NAME
WHERE
    KCU.TABLE_NAME = 'TABLE_NAME' AND
    KCU.COLUMN_NAME = 'TABLE_COLUMN_NAME'
IF @ConstraintName IS NOT NULL EXEC('alter table TABLE_NAME drop  CONSTRAINT ' + @ConstraintName)

它会根据特定的表和列删除外键约束。

如果您知道实际约束的名称，James的答案就很管用。棘手的是，在遗留和其他现实场景中，您可能不知道约束被称为什么。

如果是这种情况，你可能会创建重复的约束，为了避免，你可以使用:

create function fnGetForeignKeyName
(
    @ParentTableName nvarchar(255), 
    @ParentColumnName nvarchar(255),
    @ReferencedTableName nvarchar(255),
    @ReferencedColumnName nvarchar(255)
)
returns nvarchar(255)
as
begin 
    declare @name nvarchar(255)

    select @name = fk.name  from sys.foreign_key_columns fc
    join sys.columns pc on pc.column_id = parent_column_id and parent_object_id = pc.object_id
    join sys.columns rc on rc.column_id = referenced_column_id and referenced_object_id = rc.object_id 
    join sys.objects po on po.object_id = pc.object_id
    join sys.objects ro on ro.object_id = rc.object_id 
    join sys.foreign_keys fk on fk.object_id = fc.constraint_object_id
    where 
        po.object_id = object_id(@ParentTableName) and 
        ro.object_id = object_id(@ReferencedTableName) and
        pc.name = @ParentColumnName and 
        rc.name = @ReferencedColumnName

    return @name
end

go

declare @name nvarchar(255)
declare @sql nvarchar(4000)
-- hunt for the constraint name on 'Badges.BadgeReasonTypeId' table refs the 'BadgeReasonTypes.Id'
select @name = dbo.fnGetForeignKeyName('dbo.Badges', 'BadgeReasonTypeId', 'dbo.BadgeReasonTypes', 'Id')
-- if we find it, the name will not be null
if @name is not null 
begin 
    set @sql = 'alter table Badges drop constraint ' + replace(@name,']', ']]')
    exec (@sql)
end