Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Changing the <code>IDENTITY</code> property is really a metadata only change. But to update the metadata directly requires starting the instance in single user mode and messing around with some columns in <code>sys.syscolpars</code> and is undocumented/unsupported and not something I would recommend or will give any additional details about.</p> <p>For people coming across this answer on SQL Server 2012+ by far the easiest way of achieving this result of an auto incrementing column would be to create a <code>SEQUENCE</code> object and set the <code>next value for seq</code> as the column default.</p> <p>Alternatively, or for previous versions (from 2005 onwards), the workaround posted on <a href="http://connect.microsoft.com/SQLServer/feedback/details/252226/allow-enabling-and-disabling-of-a-columns-identity-property" rel="noreferrer">this connect item</a> shows a completely supported way of doing this without any need for size of data operations using <code>ALTER TABLE...SWITCH</code>. Also blogged about on MSDN <a href="http://blogs.msdn.com/b/dfurman/archive/2010/04/20/adding-the-identity-property-to-a-column-of-an-existing-table.aspx" rel="noreferrer">here</a>. Though the code to achieve this is not very simple and there are restrictions - such as the table being changed can't be the target of a foreign key constraint.</p> <h2>Example code.</h2> <h3>Set up test table with no <code>identity</code> column.</h3> <pre><code>CREATE TABLE dbo.tblFoo ( bar INT PRIMARY KEY, filler CHAR(8000), filler2 CHAR(49) ) INSERT INTO dbo.tblFoo (bar) SELECT TOP (10000) ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM master..spt_values v1, master..spt_values v2 </code></pre> <h3>Alter it to have an <code>identity</code> column (more or less instant).</h3> <pre><code>BEGIN TRY; BEGIN TRANSACTION; /*Using DBCC CHECKIDENT('dbo.tblFoo') is slow so use dynamic SQL to set the correct seed in the table definition instead*/ DECLARE @TableScript nvarchar(max) SELECT @TableScript = ' CREATE TABLE dbo.Destination( bar INT IDENTITY(' + CAST(ISNULL(MAX(bar),0)+1 AS VARCHAR) + ',1) PRIMARY KEY, filler CHAR(8000), filler2 CHAR(49) ) ALTER TABLE dbo.tblFoo SWITCH TO dbo.Destination; ' FROM dbo.tblFoo WITH (TABLOCKX,HOLDLOCK) EXEC(@TableScript) DROP TABLE dbo.tblFoo; EXECUTE sp_rename N'dbo.Destination', N'tblFoo', 'OBJECT'; COMMIT TRANSACTION; END TRY BEGIN CATCH IF XACT_STATE() &lt;&gt; 0 ROLLBACK TRANSACTION; PRINT ERROR_MESSAGE(); END CATCH; </code></pre> <h3>Test the result.</h3> <pre><code>INSERT INTO dbo.tblFoo (filler,filler2) OUTPUT inserted.* VALUES ('foo','bar') </code></pre> <h3>Gives</h3> <pre><code>bar filler filler2 ----------- --------- --------- 10001 foo bar </code></pre> <h3>Clean up</h3> <pre><code>DROP TABLE dbo.tblFoo </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POSQL Server, How to set auto increment after creating a table without data loss?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USMartin Smith
    1. USMartin Smith
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POSQL Server, How to set auto increment after creating a table without data loss?
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    1. CO+1 Neat trick, I wasn't aware of this workaround. Seems pretty obscure and undocumented, I don't think folks should get down-voted if they didn't know about it.
      singulars
      1. PO
      1. USAaron Bertrand
    2. CO@AaronBertrand - Agree. Wasn't my DV on the other question.
      singulars
      1. PO
      1. USMartin Smith
    3. COShould be noted also that version is important. `SWITCH` won't work pre-2005. I wish tagging `sql-server` also required specifying a minimum version. Not saying that for the benefit of this question, but the one that might get closed as a duplicate of this one.
      singulars
      1. PO
      1. USAaron Bertrand
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload