I would like to change increment value of IDENTITY column in database and I have below restrictions:
Can't drop the column.
Having around 20k rows.
Dropping table and recreate table with changed increment value would be the solution. I don't know the syntax.
Can you please suggest the syntax or other best possible solution?
Thanks in Advance!
If i understand you correctly base on your response to my comment, you backed up the data of the orig table in temp table, then you deleted the orig table and you want to recreate an orig table.
If that is the case , you need the IDENTITY_INSERT to set ON and OFF, because the identity of the table is unique.
The syntax is:
SET IDENTITY_INSERT [TableName] ON -- set to on
-- Put your insert statement here
-- insert the data from backed up temp table to your new table
SET IDENTITY_INSERT [TableName] OFF -- set to off
If you can accept recreating table, there is no magic about the recreating table syntax.
CREATE TABLE temp_Table
(
-- Identity column with new settings
-- other columns
);
INSERT INTO temp_Table
SELECT -- Columns except identity column
FROM old_table;
DROP TABLE old_Table;
EXEC sp_rename 'temp_Table', 'old_Table';
However, you have to handle foreign key by yourself.
Altering identity column after table creation is not possible.
Instead, reset SEED value using the below command.
DBCC CHECKIDENT('tablename', RESEED, 15)
Related
I have the following table :
CREATE TABLE Seq2 (val INT NOT NULL IDENTITY);
How to populate this table knowing that I tried this :
INSERT INTO Seq2(val) VALUES (1)
I have the following error :
Cannot insert explicit value for identity column in table 'Seq2' when
IDENTITY_INSERT is set to OFF.
Having such a table seems completely pointless, if I must say. If the table has only an IDENTITY then it effectively holds no meaning, so there's no point it being there.
That being said, if you did have such a table, you can INSERT values into the IDENTITY using DEFAULT VALUES:
INSERT INTO dbo.Seq2
DEFAULT VALUES;
INSERT INTO dbo.Seq2
DEFAULT VALUES;
With a new table, this would create rows with the values 1 and 2.
If you want to explicitly INSERT values into the table, then you're better off remove the IDENTITY option. Considering this is a new table, just DROP it and recreate it with the IDENTITY property:
DROP TABLE dbo.Seq2;
GO
CREATE TABLE Seq2 (val INT NOT NULL);
Having a table with a single IDENTITY column, that you're then going to define the results for really is pointless. Either don't use IDENTITY and define the values, or use IDENTITY and let SQL Server handle it.
SET IDENTITY_INSERT Seq2 ON
INSERT INTO Seq2(val)VALUES (1)
SET IDENTITY_INSERT Seq2 OFF
Simply, enable IDENTITY_INSERT for the table. That looks like this:
SET IDENTITY_INSERT IdentityTable ON
INSERT INTO Seq2(val) VALUES (1)
SET IDENTITY_INSERT IdentityTable OFF
Keep in mind :
It can only be enabled on one table at a time. If you try to enable
it on a second table while it is still enabled on a first table SQL
Server will generate an error.
When it is enabled on a table you must specify a value for the
identity column.
The user issuing the statement must own the object, be a system
administrator (sysadmin role), be the database owner (dbo) or be a
member of the db_ddladmin role in order to run the command.
SELECT SCOPE_IDENTITY() // to get last identity value generated in the same session and scope
SELECT ##IDENTITY // to get the last identity vaue generated in a session irrespective of scope
I'm attempting to create a 'history' table that gets updated every time a row on the source table is updated.
Here's the (SQL Server) code I'm using to create the history table:
DROP TABLE eventGroup_History
SELECT
CAST(NULL AS UNIQUEIDENTIFIER) AS NewId,
CAST(NULL AS varchar(255)) AS DoneBy,
CAST(NULL AS varchar(255)) AS Operation,
CAST(NULL AS datetime) AS DoneAt,
*
INTO
eventGroup_History
FROM
eventGroup
WHERE
1 = 0
GO
ALTER TABLE eventGroup_History
ALTER COLUMN NewId UNIQUEIDENTIFIER NOT NULL
go
ALTER TABLE eventGroup_History
ADD PRIMARY KEY (NewId)
GO
ALTER TABLE eventGroup_History
ADD CONSTRAINT DF_eventGroup_History_NewId DEFAULT NewSequentialId() FOR NewId
GO
The trigger is created like this:
drop trigger eventGroup_LogUpdate
go
create trigger eventGroup_LogUpdate
on dbo.eventGroup
for update
as
declare #Now as DateTime = GetDate()
set nocount on
insert into eventGroup_History
select #Now, SUser_SName(), 'update-deleted', *
from deleted
insert into eventGroup_History
select SUser_SName(), 'update-inserted', #Now, *
from inserted
go
exec sp_settriggerorder #triggername = 'eventGroup_LogUpdate', #order = 'last', #stmttype = 'update'
But when I update a row in SQL Server Management Studio, I get a message:
The data in row 2 was not committed.
Error Source: .Net SqlClient Data Provider.
Error Message: Conversion failed when converting from a character string to uniqueidentifier.
I think that the trigger is attempting to insert the SUserSName() as the first column of the row but that is the PK NewId:
There are no other uniqueidentifier columns in the table.
If I add row from the SQL Management Studio's edit grid, the row gets added without me having to specify the NewId value.
So, why is the SQL Server trigger attempting to populate NewId with first item in the INSERT INTO clause rather than skipping it to let the normal IDENTITY operation provide a value?
(And how do I stop this happening so that the trigger works?)
Because the automatic skipping only applies to IDENTITY columns - a GUID column set with the NewSequentialId() constraint behaves similarly to IDENTITY in many ways but not this one.
You can achieve what you are looking for by specifying the columns for the INSERT explicitly.
If you're going to use a default value on your NewId column, you need to explicitly list the column names in the INSERT statements. By default, SQL Server will insert the columns in the order they're listed in the SELECT, unless you give it enough information to do otherwise. Listing out the columns explicitly is a best practice, one way or the other, in order to avoid just this sort of unanticipated result.
So your statements will end up looking like this:
INSERT INTO eventGroup_History
(
DoneBy,
Operation,
DoneAt,
<All the other columns that are masked by the *>
)
SELECT....
I have a database in which all the tables have column named ID. I need to alter all tables in database and add identity to these columns. Is it possible with some query ? Or do I have to do it manually?
Thank you very much.
Unfortunately in SQL Server you cannot add identity property to existing columns. You need to drop an existing one, then create new with this property. You can automate this task by quering system tables and using dynamic sql. But if you already have some data in ID column this will make things more tricky because you need to preserve existing data.
Here is a script for a single table, automating this for all tables in database using dynamic sql will be kinda tricky...
Table Test_table has 2 columns: id and val.
-- Move data to temp storage
SELECT ID,
VAL
INTO #temp_table
FROM dbo.test_table
-- Remove data from original table
DELETE
FROM dbo.test_table
-- Drop and Create ID column
ALTER TABLE dbo.test_table
DROP COLUMN ID
ALTER TABLE dbo.test_table
ADD ID int IDENTITY(1,1)
-- Move data back to original table
SET IDENTITY_INSERT dbo.test_table ON
INSERT INTO dbo.test_table (ID, VAL)
SELECT ID, VAL
FROM #temp_table
DECLARE #MaxID int
SELECT #MaxID = MAX(ID) + 1
FROM dbo.test_table
SET IDENTITY_INSERT dbo.test_table OFF
-- Reseed IDENTITY property
DBCC CHECKIDENT ('dbo.test_table', RESEED, #MaxID)
There is no way to do this for all tables. Here's what I'd do: Use T-SQL to generate a (big) script that performs all the changes, then manually run that script.
You can add the identity property to existing columns without data movement using SWITCH.
In our database there is a table which is created with ANSI_NULLS OFF. Now we have created a view using this table. And we want to add a clustered index for this view.
While creating the clustered index it is showing an error like can't create an index since the ANSI_NULL is off for this particular table.
This table contains a large amount of data. So I want to change this option to ON without losing any data.
Is there any way to alter the table to modify this option . Please give your suggestions.
This was cross posted on Database Administrators so I might as well post my answer from there here too to help future searchers.
It can be done as a metadata only change (i.e. without migrating all the data to a new table) using ALTER TABLE ... SWITCH.
Example code below
/*Create table with option off*/
SET ANSI_NULLS OFF;
CREATE TABLE dbo.YourTable (X INT)
/*Add some data*/
INSERT INTO dbo.YourTable VALUES (1),(2),(3)
/*Confirm the bit is set to 0*/
SELECT uses_ansi_nulls, *
FROM sys.tables
WHERE object_id = object_id('dbo.YourTable')
GO
BEGIN TRY
BEGIN TRANSACTION;
/*Create new table with identical structure but option on*/
SET ANSI_NULLS ON;
CREATE TABLE dbo.YourTableNew (X INT)
/*Metadata only switch*/
ALTER TABLE dbo.YourTable SWITCH TO dbo.YourTableNew;
DROP TABLE dbo.YourTable;
EXECUTE sp_rename N'dbo.YourTableNew', N'YourTable','OBJECT';
/*Confirm the bit is set to 1*/
SELECT uses_ansi_nulls, *
FROM sys.tables
WHERE object_id = object_id('dbo.YourTable')
/*Data still there!*/
SELECT *
FROM dbo.YourTable
COMMIT TRANSACTION;
END TRY
BEGIN CATCH
IF XACT_STATE() <> 0
ROLLBACK TRANSACTION;
PRINT ERROR_MESSAGE();
END CATCH;
WARNING: when your table contains an IDENTITY column you need to reseed the IDENTITY value.
The SWITCH TO will reset the seed of the identity column and if you do not have a UNIQUE or PRIMARY KEY constraint on the identity (e.g. when using CLUSTERED COLUMNSTORE index in SQL 2014) you won't notice it right away.
You need to use DBCC CHECKIDENT ('dbo.YourTable', RESEED, [reseed value]) to correctly set the seed value again.
Unfortunately, there is no way how to do it without recreating. You need to create new table with ANSI_NULLS ON and copy there all data.
It should be something like:
SET ANSI_NULLS ON;
CREATE TABLE new_MyTBL (
....
)
-- stop all processes changing your data at this point
SET IDENTITY_INSERT new_MyTBL ON
INSERT new_MyTBL (...) -- including IDENTITY field
SELECT ... -- including IDENTITY field
FROM MyTBL
SET IDENTITY_INSERT new_MyTBL OFF
-- alter/drop WITH SCHEMABINDING objects at this point
EXEC sp_rename #objname = 'MyTBL', #newname = 'old_MyTBL'
EXEC sp_rename #objname = 'new_MyTBL', #newname = 'MyTBL'
-- alter/create WITH SCHEMABINDING objects at this point
-- re-enable your processes
DROP TABLE old_MyTBL -- do that when you are sure that system works OK
If there are any depending objects, they will work with new table as soon as you rename it. But if some of them are WITH SCHEMABINDING you need to DROP and CREATE them manualy.
I tried the SWITCH option recommended above but was unable to RESEED the identity. I could not find out why.
I used the following alternative approach instead:
Create database snapshot for the database that contains the table
Script table definition of the table you intend to update
Delete the table that you intend to update (Make sure the database snapshot is successfully created)
Update SET ANSI NULLs from OFF to ON from the script obtained from step 2 and run updated script. Table is now recreated.
Populate data from database snapshot to your table:
SET IDENTITY_INSERT TABLE_NAME ON
INSERT INTO TABLE_NAME (PK, col1, etc.)
SELECT PK, col1, etc.
FROM [Database_Snapshot].dbo.TABLE_NAME
SET IDENTITY_INSERT TABLE_NAME OFF
Migrate non clustered index manually (get script from database snapshot)
Using the above:
I did not have to worry about constraints and keys since table/constraint names always remain the same (I do not need to rename anything)
I have a backup of my data (the snapshot) which I can rely on to double check that nothing is missing.
I do not need to reseed the identity
I realize deleting table may not always be straightforward if table is referenced in other tables. That was not the case for me in this instance.. I was lucky.
Following statement can reset seed
DBCC CHECKIDENT ('TableName', RESEED, 1)
but this time I have to change its increment .
Or you can use Sql Server Management Studio:
Using this approach will most likely recreate the table.
Hope this helps
ALTER TABLE MyCustomers
ALTER COLUMN CustId IDENTITY (200, 2)
Code from ms-help://MS.VSCC.v90/MS.MSDNQTR.v90.en/ssmprog3/html/5719d3e4-14db-4073-bed7-d08f39416a39.htm
We can't update a column's identity to increment by 2 on each entry. The easiest method is to create another table with IDENTITY(1,2) and move the data to that table before dropping the actual table. Please go through the script below.
Let TableA is our actual table.
CREATE TABLE TableB(col1 INT IDENTITY (1,2) NOT NULL, col2 VARCHAR(10) NULL);
INSERT INTO TableB SELECT col2 FROM TableA;
DROP TABLE TableA;
sp_rename TableB, TableA;
You can reset the auto increment to a higher value by
Set IDENTITY_INSERT off
Running an insert statement with ID set to where you want to continue from
Set IDENTITY_INSERT on
Delete the row created (assuming it was only done to increment seed)
For example;
Table 'People' with last ID = 10 can be set to continue from 400,000 by;
SET IDENTITY_INSERT AccessToken off
insert into People(Id, name) values (400000,'Bob')
SET IDENTITY_INSERT AccessToken on
Delete from People where ID = 400000