In SQL Server (in my case, 2005) how can I add the identity property to an existing table column using T-SQL?
Something like:
alter table tblFoo
alter column bar identity(1,1)
I don't beleive you can do that. Your best bet is to create a new identity column and copy the data over using an identity insert command (if you indeed want to keep the old values).
Here is a decent article describing the process in detail:
http://www.mssqltips.com/tip.asp?tip=1397
The solution posted by Vikash doesn't work; it produces an "Incorrect syntax" error in SQL Management Studio (2005, as the OP specified). The fact that the "Compact Edition" of SQL Server supports this kind of operation is just a shortcut, because the real process is more like what Robert & JohnFX said--creating a duplicate table, populating the data, renaming the original & new tables appropriately.
If you want to keep the values that already exist in the field that needs to be an identity, you could do something like this:
CREATE TABLE tname2 (etc.)
INSERT INTO tname2 FROM tname1
DROP TABLE tname1
CREATE TABLE tname1 (with IDENTITY specified)
SET IDENTITY_INSERT tname1 ON
INSERT INTO tname1 FROM tname2
SET IDENTITY_INSERT tname1 OFF
DROP tname2
Of course, dropping and re-creating a table (tname1) that is used by live code is NOT recommended! :)
Is the table populated? If not drop and recreate the table.
If it is populated what values already exist in the column? If they are values you don't want to keep.
Create a new table as you desire it, load the records from your old table into your new talbe and let the database populate the identity column as normal. Rename your original table and rename the new one to the correct name :).
Finally if the column you wish to make identity currently contains primary key values and is being referenced already by other tables you will need to totally re think if you're sure this is what you want to do :)
There is no direct way of doing this except:
A) through SQL i.e.:
-- make sure you have the correct CREATE TABLE script ready with IDENTITY
SELECT * INTO abcTable_copy FROM abcTable
DROP TABLE abcTable
CREATE TABLE abcTable -- this time with the IDENTITY column
SET IDENTITY_INSERT abcTable ON
INSERT INTO abcTable (..specify all columns!) FROM (..specify all columns!) abcTable_copy
SET INDENTITY_INSERT abcTable OFF
DROP TABLE abcTable_copy
-- I would suggest to verify the contents of both tables
-- before dropping the copy table
B) Through MSSMS which will do exactly the same in the background but will less fat-fingering.
In the MSSMS Object Explorer right click the table you need to modify
Select "design" Select the column you'd like to add IDENTITY to
Change the identity setting from NO -> YES (possibly seed)
Ctr+S the table
This will drop and recreate the table with all original data in it.
If you get a warning:
Go to MSSMS Tools -> Options -> Designers -> Table and database Designers
and uncheck the option "Prevent saving changes that require table re-creation"
Things to be careful about:
your DB has enough disk space before you do this
the DB is not in use (especially the table you are changing)
make sure to backup your DB before doing it
if the table has a lot of data (over 1G) try it somewhere else first
before using in real DB
Create a New Table
SELECT * INTO Table_New FROM Table_Current WHERE 1 = 0;
Drop Column from New Table
Alter table Table_New drop column id;
Add column with identity
Alter table Table_New add id int primary key identity;
Get All Data in New Table
SET IDENTITY_INSERT Table_New ON;
INSERT INTO Table_New (id, Name,CreatedDate,Modified)
SELECT id, Name,CreatedDate,Modified FROM Table_Current;
SET IDENTITY_INSERT Table_New OFF;
Drop old Table
drop table Table_Current;
Rename New Table as old One
EXEC sp_rename 'Table_New', 'Table_Current';
alter table tablename
alter column columnname
add Identity(100,1)
Related
I have to change the auto increment on ID to explicitly define ID. For this I Go to
datatabse-> tables -> mytable -> design. There I set is dentity (under identity specification) to No. But when I click save it throws an error saying.
Saving changes is not permitted. The changes you have made require the following tables to
be droped and re created....
Is there any way to do it without dropping the table. I searched this error and got the solution to run a following query
SET IDENTITY_INSERT mytable ON GO
But when I try to insert from code, it throws error that
Cannot insert explicit value for identity column in table 'mytable' when IDENTITY_INSERT is set to OFF
Is there any way to get out of this problem
Once identity, always identity. You cannot change the identity property on a column. Technically, you could use IDENTITY_INSERT to get around it, but this requires setting the option on every single insert you do (this setting doesn't persist over sessions). This is probably not what you want.
Your only alternative, if recreating the table isn't an option, is to create a new column that isn't an identity column, then dropping the old one:
ALTER TABLE MyTable ADD NotAnID INT NULL;
GO
BEGIN TRANSACTION
UPDATE MyTable SET NotAnID = ID;
ALTER TABLE MyTable ALTER COLUMN NotAnID INT NOT NULL;
ALTER TABLE MyTable DROP COLUMN ID;
EXECUTE sp_rename 'MyTable.NotAnID', 'ID';
COMMIT;
This assumes your identity column is NOT NULL (as it usually is), that ID is not the primary key, that it isn't participating in foreign key constraints, and that you want the new column to take place of the old one.
If ID is the primary key, this exercise gets more involved because you need to drop the primary key constraint and recreate it -- which has its own challenges. Doubly so if it's also the clustered index. In this case, you are probably better off recreating the table anyway, because recreating the clustered index means the whole table is rewritten -- this will almost certainly interrupt production work, so you may as well let SSMS do the tough work for you. To allow that, go to Tools -> Options -> Designers and uncheck "Prevent saving changes that require table re-creation".
I have created a table with employee id as identity column. Now, I want to remove identity and replace datatype as bigint. I am using Sql Compact edition. How to achieve this?
I don't believe you can, using TSQL, remove the IDENTITY property from a column.
Instead:
Add a new BIGINT column to the table
Copy the data from the current IDENTITY field into the new field
Drop the existing column
Rename the new column to the correct name
You can do it in SSMS in the Design view for the table. I believe behind the scenes it does something like above.
Update:
To confirm, in SSMS 2K8 when you try to remove the IDENTITY property from a column and then save it, it will actually recreate the table (you can see what it does exactly by monitoring in SQL Profiler). In order to do it in SSMS, you need to ensure you have the "Prevent saving changes that require table re-creation" option turned OFF in Tools-> Options -> Designers -> Table and Database Designers. I think it defaults to ON, which would result in an error message when you try to do it otherwise.
In "real" SQL Server, you'd have to do these steps - not sure if SQL Server CE allows the same, but give it a try! I'm assuming you probably have your PRIMARY KEY constraint on that column, too - right? If not, you don't need to do the first and last step. And I'm assuming you want to have the IDENTITY on the column again, right?
-- DROP the primary key constraint (if you have that on your column)
ALTER TABLE dbo.Employees
DROP CONSTRAINT PK__Employees__3214EC274222D4EF
-- ALTER the datatype into BIGINT
ALTER TABLE dbo.Employees
ALTER COLUMN Employee_ID BIGINT
-- set PK constraint again
ALTER TABLE dbo.Employees
ADD CONSTRAINT PK_Employees PRIMARY KEY(Employee_ID)
This should help - http://www.sqlmag.com/Files/23/22081/Listing_03.txt
In all my searching I see that you essentially have to copy the existing table to a new table to chance to identity column for pre-2008, does this apply to 2008 also?
thanks.
most concise solution I have found so far:
CREATE TABLE Test
(
id int identity(1,1),
somecolumn varchar(10)
);
INSERT INTO Test VALUES ('Hello');
INSERT INTO Test VALUES ('World');
-- copy the table. use same schema, but no identity
CREATE TABLE Test2
(
id int NOT NULL,
somecolumn varchar(10)
);
ALTER TABLE Test SWITCH TO Test2;
-- drop the original (now empty) table
DROP TABLE Test;
-- rename new table to old table's name
EXEC sp_rename 'Test2','Test';
-- see same records
SELECT * FROM Test;
we cannot add identity to an existing column using sql command but we can do it using GUI.
Right click on the table - design - select the column on which you want to add identity.
go to the properties available below. find the identity specification and set it to yes.
save the table.
if it is not saved the go to tools from the menu - options - table designer - uncheck the checkbox prevent saving changes. now you can save the table modifications.
now your existing table had identity.
In all of the new feature documents I read about 2008, adding identity to an existing column was not a feature I recall. The solution you've found is correct and I think the process of adding identity increment to a column automatically would be only rarely useful.
Well you can do something like this.
ALTER TABLE my_table ADD ID_COLUMN INT IDENTITY (1,1) NOT NULL
You can add the IDENTITY property to an existing column using the GUI of Enterprise Manager / Management Studio.
In SQL 2005 and earlier, you could not modify an existing column to become an identity column. I deem it very very unlikely that MS changed that in 2008.
Is it possible to add a column to a table at a specific ordinal position in Microsoft SQL Server?
For instance, our tables always have CreatedOn, CreatedBy, LastModifiedOn, LastModifiedBy columns at the "end" of each table definition? I'd like the new column to show up in SSMS above these columns.
If I am scripting all my database changes, is there a way to preserve this order at the end of the table?
FYI, I'm not trying to institute a flame war on if this should even be done. If you want to read about a thread that degenerates quickly into that, here's a good one:
http://www.developersdex.com/sql/message.asp?p=581&r=5014513
You have to create a temp table that mirrors the original table's schema but with the column order that you want, then copy the contents of the original to temp. Delete the original and rename the temp.
This is what SQL Management Studio does behind the scenes.
With a schema sync tool, you can generate these scripts automatically.
go into SQL Server management Studio, and "design" an existing table. Insert a column in the middle, right click in an empty area and select Generate Change Script...
Now look at the script it creates. it will basically create a temp table with the proper column order, insert the data from the original table, drop the original table, and rename the temp table. This is probably what you'll need to do.
You may also need to uncheck this option to allow creation of change scripts
The answer is yes, it is technically possible, but you will have a headache doing so and it will take a long time to execute and set up.
One: Create/Copy/Drop/Rename
This is actually what SQL Server is doing in the graphical interface: here's an example of the script it is generating and executing when you click the 'save' button after adding a new column to the beginning of a table.
/* To prevent any potential data loss issues, you should review this script in detail before running it outside the context of the database designer.*/
BEGIN TRANSACTION
SET QUOTED_IDENTIFIER ON
SET ARITHABORT ON
SET NUMERIC_ROUNDABORT OFF
SET CONCAT_NULL_YIELDS_NULL ON
SET ANSI_NULLS ON
SET ANSI_PADDING ON
SET ANSI_WARNINGS ON
COMMIT
BEGIN TRANSACTION
GO
CREATE TABLE dbo.Tmp_SomeTable
(
MyNewColumn int NOT NULL,
OriginalIntColumn int NULL,
OriginalVarcharColumn varchar(100) NULL
) ON [PRIMARY]
TEXTIMAGE_ON [PRIMARY]
GO
ALTER TABLE dbo.Tmp_SomeTable SET (LOCK_ESCALATION = TABLE)
GO
SET IDENTITY_INSERT dbo.Tmp_SomeTable ON
GO
IF EXISTS(SELECT * FROM dbo.SomeTable)
EXEC('INSERT INTO dbo.Tmp_SomeTable (OriginalIntColumn, OriginalVarcharColumn FROM dbo.SomeTable WITH (HOLDLOCK TABLOCKX)')
GO
SET IDENTITY_INSERT dbo.Tmp_SomeTable OFF
GO
DROP TABLE dbo.SomeTable
GO
EXECUTE sp_rename N'dbo.Tmp_SomeTable', N'SomeTable', 'OBJECT'
GO
GO
COMMIT
Two: ADD COLUMN / UPDATE / DROP COLUMN / RENAME
This method basically involves creating a copy of any existing columns that you want to add to the 'right' of your new column, transferring the data to the new column, then dropping the originals and renaming the new ones. This will play havoc with any indexes or constraints you have, since you have to repoint them. It's technically possible, but again time-consuming both in terms of development and execution.
CREATE TABLE MyTest (a int, b int, d int, e int)
INSERT INTO MyTest (a,b,d,e) VALUES(1,2,4,5)
SELECT * FROM MyTest -- your current table
ALTER TABLE MyTest ADD c int -- add a new column
ALTER TABLE MyTest ADD d_new int -- create copies of the existing columns you want to move
ALTER TABLE MyTest ADD e_new int
UPDATE MyTest SET d_new = d, e_new = e -- transfer data to the new columns
ALTER TABLE MyTest DROP COLUMN d -- remove the originals
ALTER TABLE MyTest DROP COLUMN e
EXEC SP_RENAME 'MyTest.d_new', 'd'; -- rename the new columns
EXEC SP_RENAME 'MyTest.e_new', 'e';
SELECT * FROM MyTest
DROP TABLE MyTest -- clean up the sample
Three: Live with it
This mightily offends my sense of order ... but sometimes, it just isn't worth reshuffling.
To my knowledge there is no known method to change the order of the column. Behind the scenes SQL Management Studio does what Jose Basilio said. And if you have a big table then it is impractical to change the column orders like this way.
You can use a "view". With SQL views you can use any order you like without getting affected by the table column changes.
I am using SSMS 18. I did in simple way
Opened design of table
positioning the required column by dragging it
And as per the answer from KM (second in thread) - uncheck the option to allow creation of change scripts refer image above.
Save the changes.
Done. Check your table now.
TFS 2013 will do this for you automatically.
Add the new column(s) to your table anyway you like, and then commit your changes to TFS. From there you can open the table's sql file in Visual Studio and manually move the order of the columns in the T-SQL CREATE script. Then you can update your target database by using VS's schema compare tool found under Tools > SQL Server > New Schema Comparison. Choose your Database project with your change as the source, and the database you want to update as the target. Compare, select the table's script, and Update. VS will drop and add automatically. All your data will be safe, and indexes too.
What i think is simple is to add the column ALTER TABLE table1 ADD .. and then create a tmp table like tmp_table1 from the select like
SELECT col1,col2,col5,col3,col4 into tmp_table1 from table1;
and then drop table1 and rename the tmp_table1 to table1, that is it. I hope it will help someone
Select all the columns into a temp table, and create a new table with the new column you want. Then drop the old table, select all the columns from the temp table, and insert them into the new table with the reordered column. No data is lost.
SELECT * FROM TEMP
SELECT * FROM originaltbl
SELECT * FROM #Stagintbl
DECLARE #ColumnName nvarchar(max);
SET #ColumnName=(SELECT
DISTINCT STUFF((
SELECT ',' + a.COLUMN_NAME
FROM (
SELECT Column_name
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME='originaltbl') a
for xml path('')
),1,1,'') AS ColumnName)
DECLARE #Sqlquery nvarchar(max)
SET #Sqlquery = 'SELECT ' + #ColumnName + ' FROM #Stagintbl' + '';
INSERT INTO originaltbl
EXECUTE(#Sqlquery)
Dirty and simple.
Export table to csv.
Insert new data at desired position.
Drop table.
Create new table with desired column specifications.
Load columns from csv to new table.
I am not sure if the thread is still active. I was having the same query with MySQL database. Right clicking the table and selecting 'ALTER' auto generated the below code. Sample provided from sakila db and it worked. Just find out the column after which you want to place your new column and use 'AFTER' keyword
ALTER TABLE `sakila`.`actor`
CHANGE COLUMN `middle_name` `middle_name` VARCHAR(50) NULL DEFAULT NULL AFTER `first_name`;
Is there an easy way to remove an identity from a table in SQL Server 2005?
When I use Management Studio, it generates a script that creates a mirror table without the identity, copies the data, drops the table, then renames the mirror table, etc. This script has 5231 lines in it because this table/column have many FK relations.
I'd feel much more comfortable running a simple alter/drop. Any ideas?
EDIT
I think I'm just going to go with the 5,231 line script from Enterprise Manager. However, I'm going to break it up into smaller parts which I can run and control better. This table "behaves" strange, if you try to delete 1 row (even one you just inserted, which is not in any other FK table), you get this error:
delete MyTable where MyPrimaryKey=1234
Msg 8621, Level 17, State 2, Line 1
The query processor ran out of stack space during query optimization. Please simplify the query.
No doubt, all the FKs. We will halt all access to our application and run in single user mode when we make these schema and related application changes. However, we need this to run fast, and I need an idea of how long it will take. I guess that I'll just have to test, test, test.
If you are on SQL Server 2005 or later, you can do this as a simple metadata change (NB: doesn't require an edition supporting partitioning as I originally stated).
Example code pilfered shamelessly from the workaround by Paul White on this Microsoft Connect Item.
USE tempdb;
GO
-- A table with an identity column
CREATE TABLE dbo.Source
(row_id INTEGER IDENTITY PRIMARY KEY NOT NULL, data SQL_VARIANT NULL);
GO
-- Some sample data
INSERT dbo.Source (data)
VALUES (CONVERT(SQL_VARIANT, 4)),
(CONVERT(SQL_VARIANT, 'X')),
(CONVERT(SQL_VARIANT, {d '2009-11-07'})),
(CONVERT(SQL_VARIANT, N'áéíóú'));
GO
-- Remove the identity property
BEGIN TRY;
-- All or nothing
BEGIN TRANSACTION;
-- A table with the same structure as the one with the identity column,
-- but without the identity property
CREATE TABLE dbo.Destination
(row_id INTEGER PRIMARY KEY NOT NULL, data SQL_VARIANT NULL);
-- Metadata switch
ALTER TABLE dbo.Source SWITCH TO dbo.Destination;
-- Drop the old object, which now contains no data
DROP TABLE dbo.Source;
-- Rename the new object to make it look like the old one
EXECUTE sp_rename N'dbo.Destination', N'Source', 'OBJECT';
-- Success
COMMIT TRANSACTION;
END TRY
BEGIN CATCH
-- Bugger!
IF XACT_STATE() <> 0 ROLLBACK TRANSACTION;
PRINT ERROR_MESSAGE();
END CATCH;
GO
-- Test the the identity property has indeed gone
INSERT dbo.Source (row_id, data)
VALUES (5, CONVERT(SQL_VARIANT, N'This works!'))
SELECT row_id,
data
FROM dbo.Source;
GO
-- Tidy up
DROP TABLE dbo.Source;
I don't believe you can directly drop the IDENTITY part of the column. Your best bet is probably to:
add another non-identity column to the table
copy the identity values to that column
drop the original identity column
rename the new column to replace the original column
If the identity column is part of a key or other constraint, you will need to drop those constraints and re-create them after the above operations are complete.
You could add a column to the table that is not an identity column, copy the data, drop the original column, and rename the new column to the old column and recreate the indexes.
Here is a link that shows an example. Still not a simple alter, but it is certainly better than 5231 lines.