sql-server-2008 - 尝试删除默认值，但收到一条消息，提示它在服务器上不存在

Question

我需要将一列的数据类型从smallint更改为bigint(设计考虑较差，不要问)。我运行TSQL

alter table dbo.Test alter column ProductionModeID bigint NULL

但是得到消息:

Msg 5074, Level 16, State 1, Line 1 The object 'DF_Test_ProductionModeID' is dependent on column 'ProductionModeID'.

Msg 4922, Level 16, State 9, Line 1 ALTER TABLE ALTER COLUMN ProductionModeID failed because one or more objects access this column.

我在dbo.Test >>约束中找到了DF_Test_ProductionModeID。 (我不知道DF_Test_ProductionModeID是如何创建的，也不知道我需要它的存在)。我按Delete键，选择“确定”按钮，并收到以下消息:

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The Default 'DF_Test_ProductionModeID' does not exist on the server. (SqlManagerUI)

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For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=10.50.1447.4+((KJ_RTM).100213-0103+)&EvtSrc=Microsoft.SqlServer.Management.Smo.ExceptionTemplates.ObjectDoesNotExist&LinkId=20476

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Program Location:

at Microsoft.SqlServer.Management.SqlManagerUI.DropObjects.DoDropObject(Int32 objectRowIndex) at Microsoft.SqlServer.Management.SqlManagerUI.DropObjects.DropAllObjects(Boolean stopOnError)

所以我现在很困惑，因为如果它不存在，那么它如何依赖列呢？

Answer 1

运行以下命令会发生什么？

ALTER table Test drop DF_Test_ProductionModeID

另请参阅How To Name Default Constraints And How To Drop Default Constraint Without A Name In SQL Server以获取更多信息