SQL Server更新时间戳列

Question

In my database I have a timestamp column. I need to update a row in the table and need to update the timestamp column. When I run an update command I get:

Cannot update a timestamp column.

How can I update the timestamp column?

Answer 1

You don't

The timestamp column is updated automatically . Perhaps you are under the impression that timestamp contains a value relating to the time? It doesn't, but simply is a number which is updated whenever a value in that record is. Think of it like a row version number .

From MSDN :

The timestamp data type is just an incrementing number and does not preserve a date or a time.

Answer 2

You don't update the timestamp column - a timestamp (now renamed rowversion ) column is automatically updated by SQL server whenever any other column in the row is updated.

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If you already knew this, but for some reason want to force the column to update, just perform an update against the row you want affected. Even if it results in no actual data change, the timestamp column will still update:

create table #T1 (
    ID int not null,
    ts timestamp not null
)
insert into #T1 (ID)
select 1 union all
select 2
select * from #T1
update #T1 set ID = ID where ID=1
select * from #T1

ID  ts
1    0x0000000000039AAF
2    0x0000000000039AB0

ID  ts
1    0x0000000000039AB1
2    0x0000000000039AB0

Answer 3

Although mine is not an answer to your question I wanted to mention how TIMESTAMP can be misunderstood.

You don't state your use of the TIMESTAMP column in your question but they fact you are trying to update it implies (to me) you are trying to record when your data changes.

Have a look at this article (there are also many others on the net) regarding using TIMESTAMP when you actually want to record the change using a DATETIME .

BOL says:

The SQL Server timestamp data type has nothing to do with times or dates. SQL Server timestamps are binary numbers that indicate the relative sequence in which data modifications took place in a database. The timestamp data type was originally implemented to support the SQL Server recovery algorithms.

As Damien_The_Unbeliever says the type has been renamed and the description says:

The rowversion data type is just an incrementing number and does not preserve a date or a time. To record a date or time, use a datetime2 data type.

Of course, if you are using the data type in the manner intended ignore all of the above :)

Answer 4

I had the same problem, my solution:

UPDATE [table]
SET [ANY_COLUMN] = [ANY_COLUMN]
WHERE ID = [ID]

like anytime when a table value change the timestamp is recalculated, I update any column to the same value therefore the timestamp is updated

Answer 5

timestamp column cannot be updated since it is server generated and is gauranteed to be unique for the entire database - if updates were allowed, which it is not, then the value is not gauranteed to be unique.

i faced same problem trying to update the timestamp column in a replicated instance because the replicated instance did not have the same timestamp value as the publisher - which caused some problems when trying to obtain the last updated record per group of records. of course, with replication, it was a simple configurationg at the publisher to enable the same timestamp value to replicate over to the subscriber.

otherwise, there is no other way to update a timestamp value.