CODEWITHSUNDEEP
sqlsql-server
Ruben Teixeira
Ruben Teixeira

Reputation: 574

How to insert an auto_increment key into SQL Server table

I want to insert rows into a table that has a unique, non auto-incremented primary key.

Is there a native SQL function to evaluate the last key and increment it or do I have to do it in two steps:

key = select max(primary.key) + 1

INSERT INTO dbo.TABLE (primary.key, field1, fiels2) VALUES (KEY, value1, value2)

Upvotes: 15

Views: 105299

Answers (6)

Олег Климовцов
Олег Климовцов

Reputation: 1

CREATE TABLE dbo.Tbl1(id INT PRIMARY KEY, val1 INT, val2 INT)
INSERT INTO dbo.Tbl1(id, val1, val2)
SELECT 
(SELECT ISNULL(MAX(id),0) FROM dbo.Tbl1 WITH(SERIALIZABLE, UPDLOCK)+ROW_NUMBER()over(order by (select 0))
, val1
, val2
FROM dbo.Tbl2;

Upvotes: 0

Aprendiz
Aprendiz

Reputation: 23

Inserting one record:

I only do this to insert a row into a table with a non auto-incremented primary key:

DECLARE @myKey int
SET @myKey = (SELECT  ISNULL(MAX(primaryKey),0) FROM dbo.myTable)

INSERT INTO dbo.myTABLE (primaryKey, field1, fiels2) VALUES (@myKey + 1, value1, value2)

Inserting multiple records:

In another situation, I needed to duplicate multiple records in a table. For this, I used an INSERT from the result of a SELECT. My intention was to duplicate some records from myTable, that meet a specific condition. But I needed to figure out how to duplicate records in a table with a unique PRIMARY KEY, without repeating an ID. Here's how I solved it:

DECLARE @myKey int 
SET @myKey = (SELECT  ISNULL(MAX(primaryKey),0) FROM dbo.myTable)

INSERT INTO dbo.myTABLE (primaryKey, field1, fiels2) 
SELECT 
     (primaryKey + @myKey, value1, value2) 
        FROM dbo.myTable 
        WHERE value2 = especific_Condition

There were some gaps in the IDs, but I enforce uniqueness PRIMARY KEY.

Upvotes: 2

PyDevSRS
PyDevSRS

Reputation: 1865

create table if not exists Emp ( eid int(10) not null primary key auto_increment, name varchar(45) not null, age int(5) default 20, salary int(5) ) insert into emp values(102,'Ranjan',21,450000);

Then try below sql query . It will automaticaly increment the eid to next number .

insert into emp (name,salary) values( 'Lisma',118500);

select * from emp;

Upvotes: 0

ErikE
ErikE

Reputation: 50211

In my opinion the best answer is to fix your table so that the PK column is an identity column. (Please see my comments on the answer from Sebastian Meine about why your currently selected answer is not best.) The only way to make an existing PK become an identity column is by swapping out the table. Roughly:

BEGIN TRAN;
-- Rename all constraints in original table
EXEC sp_rename 'dbo.YourOriginalTable.PK_ConstraintName', 'PKConstraint_Backup';
EXEC sp_rename 'dbo.YourOriginalTable.OtherConstraintName', 'OtherConstraintName_Backup';
CREATE TABLE dbo.WorkTable (
    YourPKColumn int identity(1, 1) NOT NULL -- your PK converted to identity
    CONSTRAINT PK_YourOriginalTableConstraintName PRIMARY KEY CLUSTERED,
    AllOtherColumns -- all your other columns exactly as in the original table
);

SET IDENTITY_INSERT dbo.WorkTable ON;
INSERT dbo.WorkTable (YourPKColumn, AllOtherColumns)
SELECT YourPKColumn, AllOtherColumns
FROM dbo.YourOriginalTable WITH (TABLOCKX, HOLDLOCK);

SET IDENTITY_INSERT dbo.WorkTable OFF;

-- Drop all FK constraints from other tables pointing to your table
ALTER TABLE dbo.TableWithFK_1
DROP CONSTRAINT FK_TableWithFK_1_YourOriginalTableSomethingID;

-- Swap out the tables
EXEC sp_rename 'dbo.YourOriginalTable', 'YourOriginalTableBackup';
EXEC sp_rename 'dbo.WorkTable', 'YourOriginalTable';

-- If you didn't add them in the WorkTable creation,
-- add all other removed or needed constraints creation
ALTER TABLE dbo.YourOriginalTable
ADD CONSTRAINT OriginalConstraint (OriginalConstraintColumns);
-- Add back FK constraints from other tables to this one.
COMMIT TRAN;

You now have a table that has an identity column with a clustered PK on it. You can insert to it no problem. No more concurrency issues and silly SELECT Max() + 1 junk that is so easy to get wrong.

Upvotes: 4

Sebastian Meine
Sebastian Meine

Reputation: 11773

Judging by you comments throughout, you have a primary key on the table that is not an identity column.

If your version of SQL Server is SQL 2012 you should look into sequences: http://msdn.microsoft.com/en-us/library/ff878091.aspx

In other versions you either need to recreate the table using the IDENTITY property (http://msdn.microsoft.com/en-us/library/aa933196(v=sql.80).aspx) for the primary key column or use a two step approach.

If you go with the two step approach you need to make sure that concurrently running inserts won't end up using the same new value. The easiest way to do that is this is by combining the select and the insert into one value and using the serializable table hint:

CREATE TABLE dbo.Tbl1(id INT PRIMARY KEY, val1 INT, val2 INT)

INSERT INTO dbo.Tbl1(id, val1, val2)
VALUES((SELECT ISNULL(MAX(id)+1,0) FROM dbo.Tbl1 WITH(SERIALIZABLE, UPDLOCK)), 42, 47);

SELECT * FROM dbo.Tbl1;

Upvotes: 15

Jordão
Jordão

Reputation: 56467

Since it's auto-generated, simply don't provide it:

INSERT INTO bo.TABLE (field1, fiels2) VALUES (value1, value2)

Update: that will work if your column is an IDENTITY column.

To provide explicit values to an identity column, you have to do this:

set identity_insert bo.TABLE on

INSERT INTO bo.TABLE (primary_key, field1, fiels2) VALUES ((SELECT ISNULL(MAX(id) + 1, 0) FROM bo.Table), value1, value2)

set identity_insert bo.TABLE off

But there's no compelling reason for doing it this way.

Upvotes: 34

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