My database(SQL server 2008) already having some records and having two sorting index on two columns. I tried to add identity column using following query. But it providing me wrong identity numbers associated with records.
alter table Table_name add RECORD_NUMBER int identity(1,1)
record which inserted first having higher number and record which is inserted last having lower number. and some records are having just opposite numbers. Is it possible to remove such kind of problem and insert right insertion order for records.
I did this because i was not having any primary key or unique or compost key in my table. So to identify which record is first entered, i introduce identity column. I was thinking that it will allocate record number according to insertion order.
If it's possible for you to move data in a new table then this is an approach which is basically recommended by Microsoft:
/*************
Preparing for the example, create tables, insert sample data,...
**************/
-- Your existing table
CREATE TABLE dbo.oldtable
(
colA int,
colB nvarchar(10)
)
-- The new table, same structure + new identity column:
CREATE TABLE dbo.newtable
(
colID int IDENTITY(1,1),
colA int,
colB nvarchar(10)
)
--create unique clustered index on new identity column
create unique clustered index ucx_newtable
on dbo.newtable (colID ASC)
--create other indexes as you need them
create index idx_newtable
on dbo.newtable (colA ASC)
--sample data
insert into dbo.oldtable(colA,colB)
values (16,'this'),(17,'is'),(225,'an'),(300,'example')
/*************
Data Movement
**************/
BEGIN TRANSACTION
BEGIN TRY
--move data to new table including new id column which is generated by
--colA, which gives us the order from old to new in this example
SET IDENTITY_INSERT dbo.newtable ON --So we can insert into the colID identity column
INSERT INTO dbo.newtable(colID, colA,colB)
SELECT ROW_NUMBER() OVER(ORDER BY colA ASC) AS colID --this will generate numbers beginning from 1
,colA, colB
FROM dbo.oldtable
SET IDENTITY_INSERT dbo.newtable OFF
--rename old table / or drop it if you want
EXEC sp_rename #objname = 'dbo.oldtable', #newname = 'dbo.oldtable_xyz'
EXEC sp_rename #objname = 'dbo.newtable', #newname = 'dbo.oldtable'
COMMIT TRANSACTION
END TRY
BEGIN CATCH
SELECT ERROR_MESSAGE()
ROLLBACK TRANSACTION
END CATCH
Related
I have multiple tables in database all table has id column which is primary key.
I want a script by which i can add identity property to all tables at once rather than I go and change one by one.
You can't alter the existing columns for identity.
You have 2 options:
Create a new table with identity & drop the existing table
Create a new column with identity & drop the existing column
But take spl care when these columns have any constraints / relations.
For already craeted table Names
Drop table Names
Create table Names
(
ID int,
Name varchar(50)
)
Insert Into Names Values(1,'SQL Server')
Insert Into Names Values(2,'ASP.NET')
Insert Into Names Values(4,'C#')
In this Approach you can retain the existing data values on the newly
created identity column
CREATE TABLE dbo.Tmp_Names
(
Id int NOT NULL IDENTITY (1, 1),
Name varchar(50) NULL
) ON [PRIMARY]
go
SET IDENTITY_INSERT dbo.Tmp_Names ON
go
IF EXISTS(SELECT * FROM dbo.Names)
INSERT INTO dbo.Tmp_Names (Id, Name)
SELECT Id, Name FROM dbo.Names TABLOCKX
go
SET IDENTITY_INSERT dbo.Tmp_Names OFF
go
DROP TABLE dbo.Names
go
Exec sp_rename 'Tmp_Names', 'Names'
In this approach you can’t retain the existing data values on the
newly created identity column;
The identity column will hold the sequence of number
Alter Table Names Add Id_new Int Identity(1,1)
Go
Alter Table Names Drop Column ID
Go
Exec sp_rename 'Names.Id_new', 'ID','Column'
Source 1
What you can do is write a quick query to generate the SQL for you
like so:
USE INFORMATION_SCHEMA;
SELECT
CONCAT("ALTER TABLE `", TABLE_SCHEMA,"`.`", TABLE_NAME, "` CONVERT TO CHARACTER SET UTF8;")
AS MySQLCMD FROM TABLES
WHERE TABLE_SCHEMA = "your_schema_goes_here";
Then you can run the output from this to do what you need.
Source 2
EDIT
You could check Altering Multiple Tables at once
I have a table in SQL Server with bundle of records. I want to convert the ID column which is Primary Key to an identity Column without loss of data. I thought of the following two approaches:
Create a new table with identity & drop the existing table.
Create a new column with identity & drop the existing column.
but it's clear that they can not be implemented because keeping records is my first priority.
Is there another way to do this?
This solution violates your point 2, but there is no other way and I think your aim is to keep the old values, because nothing else makes sense...
You could do the following:
make it possible to insert into identity columns in your table:
set identity_insert YourTable ON
add a new ID column to your table with identity and insert the values from your old columns
turn identity insert off
set identity_insert YourTable OFF
delete old ID column
rename new column to old name
make it to the primary key
The only problem could be that you have your ID column already connected as foreign key to other tables. Then you have a problem with deleting the old column...
In this case you have to drop the foreign key constraints on your ID column after step 3, then do step 4 to 6 and then recreate your foreign key constraints.
As you are using SQL Server 2012, another possible alternative could be to create a sequence object that has a starting value of the highest ID +1 already in your table, then create a default constraint for your column using GET NEXT VALUE FOR and reference your sequence object you just created.
If you have direct access to the Server Database, just go into the design of the table, select the PK column, and change the identity to "Yes". Make sure you set your seed to the max value of that column. The increment is 1 by default. Save the table design and you should be good to go.
Considering the source table isn't too big:
Create new table (with IDENTITY)
Populate new table from existing table (with IDENTITY_INSERT ON)
Drop old table (drop any existing FKs first)
Rename new table to old name (re-establish FKs if needed)
-- Create Sample Existing Table
DROP TABLE IF EXISTS #tblTest
CREATE TABLE #tblTest
(
ID INT NOT NULL
, Val VARCHAR(10) NOT NULL
)
INSERT INTO #tblTest
(
ID
, Val
)
VALUES
(1, 'a')
, (2, 'b')
, (4, 'c')
GO
-- Create and Populate New Table (with IDENTITY_INSERT ON)
DROP TABLE IF EXISTS #tblTestNew
CREATE TABLE #tblTestNew
(
ID INT IDENTITY(1, 1) NOT NULL
, Val VARCHAR(10) NOT NULL
)
SET IDENTITY_INSERT #tblTestNew ON
INSERT INTO #tblTestNew
(
ID
, Val
)
(
SELECT
#tblTest.ID
, #tblTest.Val
FROM
#tblTest
)
SET IDENTITY_INSERT #tblTestNew OFF
GO
-- Rename Existing Table to Old (can use sp_rename instead, but I can't for temp tables)
SELECT * INTO #tblTestOld FROM #tblTest
DROP TABLE #tblTest
GO
-- Rename New Table to Existing (can use sp_rename instead, but I can't for temp tables)
SELECT * INTO #tblTest FROM #tblTestNew
DROP TABLE #tblTestNew
GO
-- Test Inserting new record
INSERT INTO #tblTest (Val)
VALUES ('d')
-- Verify Results
SELECT * FROM #tblTest
EXEC tempdb.sys.sp_help #objname = N'#tblTest'
-- Drop 'Old' Table (when ready)
DROP TABLE IF EXISTS #tblTestOld
-- Cleanup
DROP TABLE IF EXISTS #tblTest
DROP TABLE IF EXISTS #tblTestNew
DROP TABLE IF EXISTS #tblTestOld
If the table is very large, consider the log growth, Recovery Model, possible single-user mode, etc.
create table t1 (col1 int, col2 varchar(10))
insert into t1 values (10, 'olddata')
--add identity col
alter table t1 add col3 int identity(1,1)
GO
--rename or remove old column
alter table t1 drop column col1
--rename new col to old col name
exec sp_rename 't1.col3', 'col1', 'column'
GO
--add new test , review table
insert into t1 values ( 'newdata')
select * from t1
I have a table that has over 7 million records in it. The table does not have a primary key. I would like to add a new identity column and set this as the primary key. I tried adding the column using SSMS, then I set it as the primary key. I called this new column Id.
This almost worked, however I wanted to change the default order of the table to be based another column, for instance a date time column in descending order. Is this possible? Perhaps I need to use a temp table and the ROW_NUMBER() function.
However, I am not very good at SQL. Can someone help?
I also need to have a rollback script so I can get back to the original table.
Here is one more idea:
Step1 - Create temporary clustered index on "date time column in descending order"
CREATE CLUSTERED INDEX ix_YourTableTEMP ON YourTable (DateTimeColumn DESC)
Step2 - Add identity column. Now the IDs should be in order of previously created index - although I don't think there is 100% guarantee on this.
ALTER TABLE YourTable ADD IdColumn INT IDENTITY(1,1)
Step3 - Drop temporary index
DROP INDEX ix_YourTableTEMP ON YourTable
Step4 - Create new clustered PK on new column
ALTER TABLE YourTable
ADD CONSTRAINT PK_YourTable PRIMARY KEY CLUSTERED (IdColumn)
The Link Martin Smith has given is probably the best answer, but here is an alternative:
-- CREATE TABLE WITH SOME DATA IN
CREATE TABLE T (X INT);
INSERT T VALUES (1), (2), (3);
-- CREATE A CLONE OF THIS TABLE, ADDING AN IDENTITY COLUMN
-- USING ORDER BY TO AFFECT THE ORDER OF THE INSERT
SELECT ID = IDENTITY(INT, 1, 1),
T.*
INTO T_Clone
FROM T
ORDER BY X DESC;
-- DROP ORIGINAL TABLE
DROP TABLE T;
-- RENAME CLONE TABLE TO ORIGINAL TABLE NAME
EXECUTE SP_RENAME 'dbo.T_Clone', 'T', 'OBJECT';
-- SELECT FROM TABLE TO CHECK RESULTS
SELECT *
FROM T;
To rollback:
ALTER TABLE T DROP COLUMN ID;
EDIT
It has been pointed out that SELECT ID = IDENTITY(INT, 1, 1).. INTO.. FROM .. ORDER BY ... does not guarantee the order of the insert. So it would appear that the fail safe option is to create your clone table using CREATE TABLE syntax and adding the IDENTITY column:
CREATE TABLE T_Clone
( ID INT IDENTITY(1, 1) NOT NULL PRIMARY KEY,
<your columns>
);
INSERT T_Clone (<your columns>)
SELECT <your columns>
FROM T
ORDER BY ...;
Then carry on with the Drop and rename as above. I can find no documentation to say this method is not reliable for ordering the insert, if it proves to still not be reliable you could use:
SET IDENTITY_INSERT T_Clone ON;
INSERT T_Clone (ID, <your columns>)
SELECT ROW_NUMBER() OVER(ORDER BY ...),
<your columns>
FROM T;
SET IDENTITY_INSERT T_Clone OFF;
Then reseed T_CLone after the insert.
I have table with 500 records in it and want to insert new column as "serial number" starting with 1.
If you care about the order in which the identity values are assigned, you are best off doing this:
CREATE TABLE dbo.NewTable
(
SerialNumber INT IDENTITY(1,1),
... other columns from original table ...
);
INSERT dbo.NewTable(...other columns...)
SELECT ...other columns...
FROM dbo.OriginalTable
ORDER BY ...ordering criteria...
OPTION (MAXDOP 1); -- to prevent parallelism from messing with identity
DROP TABLE dbo.OriginalTable;
EXEC sp_rename N'dbo.NewTable', N'OriginalTable', N'OBJECT';
You may have to deal with constraints etc. and you will want to do this in a transaction. The point is that just adding an identity column to the table with assign the identity values in an arbitrary order. If you don't care about how the existing values are assigned serial numbers, then just use Kyle's answer.
This could be achieved as follows:
alter table YourTable
add SrNo int identity(1,1)
in PostgreSQL just do:
ALTER TABLE ttaabbllee ADD COLUMN columnName serial NOT NULL; and done!..
How can I modify table and set identity on PK column using T-SQL?
thanks for help
You can't modify an existing column to have the IDENTITY "property" - you have to:
create a new table with the same structure (but with IDENTITY set up),
turn on IDENTITY_INSERT for this new table,
insert rows from the old table into the new table,
drop the old table, and,
rename the new table to have the old table name.
If there are foreign keys involved, you need to fix those up also.
The problem with most solutions to this question is that they require either adding a new column to the table or completely rebuilding the table.
Both can require large amounts of locking and logging activity which I have always found annoying as this is a metadata only change and shouldn't necessitate touching the data pages at all (Indeed it is possible to update the metadata directly by starting the instance in single user mode and messing around with some columns in sys.syscolpars but this is undocumented/unsupported.)
However the workaround posted on this connect item shows a completely supported way of making this into a metadata only change using ALTER TABLE...SWITCH (credit SQLKiwi)
Example code.
Set up test table with no identity column.
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
Alter it to have an identity column (more or less instant).
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() <> 0 ROLLBACK TRANSACTION;
PRINT ERROR_MESSAGE();
END CATCH;
Test the result.
INSERT INTO dbo.tblFoo (filler,filler2)
OUTPUT inserted.*
VALUES ('foo','bar')
Gives
bar filler filler2
----------- --------- ---------
10001 foo bar
Clean up
DROP TABLE dbo.tblFoo
Is it the answer you are looking for?
DBCC CHECKIDENT(
'DBName.dbo.TableName'
,RESEED --[, new_reseed_value ]
)
Example use:
DBCC CHECKIDENT(
'DBName.dbo.TableName'
)
Checking identity information: current identity value '1', current column value '1211031236'.
DBCC execution completed. If DBCC printed error messages, contact your system administrator.
DBCC CHECKIDENT(
'DBName.dbo.TableName'
,RESEED --[, new_reseed_value ]
)
Checking identity information: current identity value '1211031236', current column value '1211031236'.
DBCC execution completed. If DBCC printed error messages, contact your system administrator.
In fact, you can modify the IDENTITY on a column.
Please read through this article http://www.sqlmag.com/article/tsql3/adding-the-identity-property-to-an-existing-column.aspx
It will need a lot more code than ALTER TABLE tab ALTER COLUMN col SET IDENTITY, though
You need to use the ALTER TABLE command - always test first in dev or pre-production!
The example G seems closest to your requirement:
CREATE TABLE dbo.doc_exe ( column_a INT CONSTRAINT column_a_un UNIQUE) ;
GO
ALTER TABLE dbo.doc_exe ADD
-- Add a PRIMARY KEY identity column.
column_b INT IDENTITY
CONSTRAINT column_b_pk PRIMARY KEY,
See http://msdn.microsoft.com/en-us/library/ms190273.aspx
Since you can only ignore identity columns for insert, not for update, you'll need an intermediate table. Here's an example:
create table TestTable (pk int constraint PK_TestTable primary key,
name varchar(30))
create table TestTable2 (pk int constraint PK_TestTable identity primary key,
name varchar(30))
set identity_insert TestTable2 on
insert TestTable2 (pk, name) select pk, name from TestTable
set identity_insert TestTable2 off
drop table TestTable
exec sp_rename 'TestTable2', 'TestTable'