将计算列转换为常规列

Question

我在SQL Server 2005中的大表中有一个持久的计算列.

我想将它转换为常规列,保持当前值.

我是否必须重新创建列并在事务中更新整个表,或者是否可以只更改计算列规范,以及如何执行此操作？

Answer 1

-- Create a new Column (unpersisted):
ALTER TABLE MyTable
   ADD newColumn DatatypeOfPersistedColumn
GO

UPDATE myTable
SET newColumn = PersistedColumn
GO

-- Delete the persisted column
ALTER TABLE MyTable
   DROP COLUMN PersistedColumn
GO

-- Rename new column to old name
EXEC sp_rename 'MyTable.newColumn', 'PersistedColumn', 'COLUMN'
GO

Answer 2

-- Create a new Column (unpersisted):
ALTER TABLE MyTable
   ADD newColumn DatatypeOfPersistedColumn

UPDATE myTable
SET newColumn = PersistedColumn

-- Delete the persisted column
ALTER TABLE MyTable
   DROP COLUMN PersistedColumn

-- Rename the new column to the old name
EXEC sp_rename 'MyTable.newColumn', 'PersistedColumn', 'COLUMN'