如果SQL Server中存在外键约束,如何删除表？

Question

我有以下内容:

DROP TABLE [dbo].[ExtraUserInformation];
DROP TABLE [dbo].[UserProfile];
DROP TABLE [dbo].[webpages_Membership];
DROP TABLE [dbo].[webpages_OAuthMembership];
DROP TABLE [dbo].[webpages_Roles];
DROP TABLE [dbo].[webpages_UsersInRoles];

CREATE TABLE [dbo].[ExtraUserInformation] (
    [Id]       INT            IDENTITY (1, 1) NOT NULL,
    [UserId]   INT            NOT NULL,
    [FullName] NVARCHAR (MAX) NULL,
    [Link]     NVARCHAR (MAX) NULL,
    [Verified] BIT            NULL,
    CONSTRAINT [PK_dbo.ExtraUserInformation] PRIMARY KEY CLUSTERED ([Id] ASC)
);

CREATE TABLE [dbo].[webpages_UsersInRoles] (
    [UserId] INT NOT NULL,
    [RoleId] INT NOT NULL,
    PRIMARY KEY CLUSTERED ([UserId] ASC, [RoleId] ASC),
    CONSTRAINT [fk_UserId] FOREIGN KEY ([UserId]) REFERENCES [dbo].[UserProfile] ([UserId]),
    CONSTRAINT [fk_RoleId] FOREIGN KEY ([RoleId]) REFERENCES [dbo].[webpages_Roles] ([RoleId])
);

然而,这是失败的消息说:

Msg 3726, Level 16, State 1, Line 6
Could not drop object 'dbo.UserProfile' because it is referenced by a FOREIGN KEY constraint.
Msg 3726, Level 16, State 1, Line 9
Could not drop object 'dbo.webpages_Roles' because it is referenced by a FOREIGN KEY constraint.
Msg 2714, Level 16, State 6, Line 27
There is already an object named 'UserProfile' in the database.
Checking identity information: current identity value 'NULL', current column value 'NULL'.
DBCC execution completed. If DBCC printed error messages, contact your system administrator.

在这种情况下如何放桌子？

Answer 1

您必须先删除约束,然后才能删除该表.否则,违反规则.如何获得外键关系看到这个老问题. SQL DROP TABLE外键约束

Answer 2

1 - 首先,在删除表之后删除外键约束.

2 - 您可以通过执行以下查询来删除所有外键:

DECLARE @SQL varchar(4000)=''
SELECT @SQL = 
@SQL + 'ALTER TABLE ' + s.name+'.'+t.name + ' DROP CONSTRAINT [' + RTRIM(f.name) +'];' + CHAR(13)
FROM sys.Tables t
INNER JOIN sys.foreign_keys f ON f.parent_object_id = t.object_id
INNER JOIN sys.schemas     s ON s.schema_id = f.schema_id

--EXEC (@SQL)

PRINT @SQL

如果你执行打印结果@SQL,外键将被删除.

Answer 3

删除包含外部约束的表的最佳答案是：

• 第 1 步：删除表的主键。
• Step 2 : 现在会提示是否删除所有的外部引用。
• 第 3 步：删除表。