I am from this link
Suppose I have a Table:
FieldWorker{ ID, Name, WorkingArea}
And, ID is an auto-incremented field.
Now, suppose, I am using the following code to insert records:
sqlComm.ExecuteNonQuery("INSERT INTO [FieldWorker]
([Name]
,[WorkingArea])
VALUES
(#Name
,#WorkingArea)");
What technique can I use to retrieve the maximum value of auto-incremented ID field that has been generated upon the insertion of the latest record?
Both the insertion-code and the retrieval of ID-value must be done under a single SqlTransaction object.
Why must I use ExecuteScalar()?
For SQL Server 2000, you'd need to do this with SCOPE_IDENTITY and ExecuteScalar
sqlComm.ExecuteScalar("INSERT INTO [FieldWorker]
([ID]
,[Name]
,[WorkingArea])
VALUES
(#ID
,#Name
,#WorkingArea);
SELECT SCOPE_IDENTITY()");
For SQL Server 2005+, you use the OUTPUT clause
sqlComm.ExecuteScalar("INSERT INTO [FieldWorker]
([ID]
,[Name]
,[WorkingArea])
OUTPUT INSERTED.ID
VALUES
(#ID
,#Name
,#WorkingArea);");
1) You can set ID as Identity (auto increment)
2) You can get the last Identity number inserted as follow
##IDENTITY
Reference SQL Identity Number
If the ID field is autoincremented you don't need to include in your insert.
Further you can use Scope_Identity().
For more information you can visit this blog
http://blog.sqlauthority.com/2007/03/25/sql-server-identity-vs-scope_identity-vs-ident_current-retrieve-last-inserted-identity-of-record/
Related
I have seen some store procedure that return select statement after insert like following. What is the usage?
SELECT
*
FROM
[dbo].[TableName]
WHERE
[PrimaryKey] = SCOPE_IDENTITY()
I agree with Millie's comment. However, if you are new to SQL Server you might find some words in docs new and may have more questions. Hopefully the explanation below will help.
https://msdn.microsoft.com/en-us/library/ms190315(v=sql.105).aspx says:
Returns the last identity value inserted into an identity column in
the same scope. A scope is a module: a stored procedure, trigger,
function, or batch. Therefore, two statements are in the same scope if
they are in the same stored procedure, function, or batch.
In your stored procedure, the INSERT statement is done on a table with an identity column. This identity column gets an incremented auto-number during the insertion process. To know what this number is, SCOPE_IDENTITY() function is used.
For example:
create table employees (id int identity(1,1) primary key, fullname varchar(100));
insert into employees (fullname) values ('John Smith');
select scope_identity(); -- will return the ID of the inserted record
SQLFiddle example: http://sqlfiddle.com/#!3/41f84/2 (keep on pressing Run SQL to see the last entered data's ID).
You can then use this auto generated ID to do some more work, such as write to an audit table, or write more data to a details table etc.
I have seen various methods used when retrieving the value of a primary key identity field after insert.
declare #t table (
id int identity primary key,
somecol datetime default getdate()
)
insert into #t
default values
select SCOPE_IDENTITY() --returns 1
select ##IDENTITY --returns 1
Returning a table of identities following insert:
Create Table #Testing (
id int identity,
somedate datetime default getdate()
)
insert into #Testing
output inserted.*
default values
What method is proper or better? Is the OUTPUT method scope-safe?
The second code snippet was borrowed from SQL in the Wild
It depends on what you are trying to do...
##IDENTITY
Returns the last IDENTITY value produced on a connection, regardless of the table that produced the value, and regardless of the scope of the statement that produced the value.
##IDENTITY will return the last identity value entered into a table in your current session. ##IDENTITY is limited to the current session and is not limited to the current scope. For example, if you have a trigger on a table that causes an identity to be created in another table, you will get the identity that was created last, even if it was the trigger that created it.
SCOPE_IDENTITY()
Returns the last IDENTITY value produced on a connection and by a statement in the same scope, regardless of the table that produced the value.
SCOPE_IDENTITY() is similar to ##IDENTITY, but it will also limit the value to your current scope. In other words, it will return the last identity value that you explicitly created, rather than any identity that was created by a trigger or a user defined function.
IDENT_CURRENT()
Returns the last IDENTITY value produced in a table, regardless of the connection and scope of the statement that produced the value. IDENT_CURRENT is limited to a specified table, but not by connection or scope.
Note that there is a bug in scope_identity() and ##identity - see MS Connect: https://web.archive.org/web/20130412223343/https://connect.microsoft.com/SQLServer/feedback/details/328811/scope-identity-sometimes-returns-incorrect-value
A quote (from Microsoft):
I highly recommend using OUTPUT instead of ##IDENTITY in all cases.
It's just the best way there is to read identity and timestamp.
Edited to add: this may be fixed now. Connect is giving me an error, but see:
Scope_Identity() returning incorrect value fixed?
There is almost no reason to use anything besides an OUTPUT clause when trying to get the identity of the row(s) just inserted. The OUTPUT clause is scope and table safe.
Here's a simple example of getting the id after inserting a single row...
DECLARE #Inserted AS TABLE (MyTableId INT);
INSERT [MyTable] (MyTableColOne, MyTableColTwo)
OUTPUT Inserted.MyTableId INTO #Inserted
VALUES ('Val1','Val2')
SELECT MyTableId FROM #Inserted
Detailed docs for OUTPUT clause: http://technet.microsoft.com/en-us/library/ms177564.aspx
-- table structure for example:
CREATE TABLE MyTable (
MyTableId int NOT NULL IDENTITY (1, 1),
MyTableColOne varchar(50) NOT NULL,
MyTableColTwo varchar(50) NOT NULL
)
##Identity is the old school way. Use SCOPE_IDENTITY() in all instances going forward. See MSDN for the repercussions of using ##IDENTITY (they're bad!).
SCOPE_IDENTITY is sufficient for single rows and is recommended except in cases where you need to see the result of an intermediate TRIGGER for some reason (why?).
For multiple rows, OUTPUT/OUTPUT INTO is your new best friend and alternative to re-finding the rows and inserting into another table.
There is another method available in SQL Server 2005 that is outlined in SQL in the Wild.
This will allow you to retrieve multiple identities after insert. Here's the code from the blog post:
Create Table #Testing (
id int identity,
somedate datetime default getdate()
)
insert into #Testing
output inserted.*
default values
A small correction to Godeke's answer:
It's not just triggers you need to worry about. Any kind of nested operation, such as stored procs, that causes identifiers to be created could change the value of ##IDENTITY.
Another vote for scope_identity...
Be carreful while using ##IDENTITY ...
http://dotnetgalactics.wordpress.com/2009/10/28/scope-identity-vs-identity/
I just want to ask how to get latest inserted ID from table A as an example and use it to enter a record in another table B?
If I got your question well, You need to perform two INSERT statements within one Stored Procedure and use the ID generated from the first statement to use it in the second statement, use SCOPE_IDENTITY()
create proc yourproc
(
-- parameter definitions here
)
as
begin
insert into Employee
(FN,LN,Address)
values
(#FN,#LN,#Address)
declare #EmployeeID int
set #EmployeeID = SCOPE_IDENTITY()
insert into EmpContact
(Empid, ContactType, ContactNumber)
values
(#EmployeeID, #ContactType, #ContactNumber)
end
SCOPE_IDENTITY and ##IDENTITY return the last identity values that are
generated in any table in the current session. However, SCOPE_IDENTITY
returns values inserted only within the current scope; ##IDENTITY is
not limited to a specific scope.
SCOPE_IDENTITY (Transact-SQL) - MSDN
I have seen various methods used when retrieving the value of a primary key identity field after insert.
declare #t table (
id int identity primary key,
somecol datetime default getdate()
)
insert into #t
default values
select SCOPE_IDENTITY() --returns 1
select ##IDENTITY --returns 1
Returning a table of identities following insert:
Create Table #Testing (
id int identity,
somedate datetime default getdate()
)
insert into #Testing
output inserted.*
default values
What method is proper or better? Is the OUTPUT method scope-safe?
The second code snippet was borrowed from SQL in the Wild
It depends on what you are trying to do...
##IDENTITY
Returns the last IDENTITY value produced on a connection, regardless of the table that produced the value, and regardless of the scope of the statement that produced the value.
##IDENTITY will return the last identity value entered into a table in your current session. ##IDENTITY is limited to the current session and is not limited to the current scope. For example, if you have a trigger on a table that causes an identity to be created in another table, you will get the identity that was created last, even if it was the trigger that created it.
SCOPE_IDENTITY()
Returns the last IDENTITY value produced on a connection and by a statement in the same scope, regardless of the table that produced the value.
SCOPE_IDENTITY() is similar to ##IDENTITY, but it will also limit the value to your current scope. In other words, it will return the last identity value that you explicitly created, rather than any identity that was created by a trigger or a user defined function.
IDENT_CURRENT()
Returns the last IDENTITY value produced in a table, regardless of the connection and scope of the statement that produced the value. IDENT_CURRENT is limited to a specified table, but not by connection or scope.
Note that there is a bug in scope_identity() and ##identity - see MS Connect: https://web.archive.org/web/20130412223343/https://connect.microsoft.com/SQLServer/feedback/details/328811/scope-identity-sometimes-returns-incorrect-value
A quote (from Microsoft):
I highly recommend using OUTPUT instead of ##IDENTITY in all cases.
It's just the best way there is to read identity and timestamp.
Edited to add: this may be fixed now. Connect is giving me an error, but see:
Scope_Identity() returning incorrect value fixed?
There is almost no reason to use anything besides an OUTPUT clause when trying to get the identity of the row(s) just inserted. The OUTPUT clause is scope and table safe.
Here's a simple example of getting the id after inserting a single row...
DECLARE #Inserted AS TABLE (MyTableId INT);
INSERT [MyTable] (MyTableColOne, MyTableColTwo)
OUTPUT Inserted.MyTableId INTO #Inserted
VALUES ('Val1','Val2')
SELECT MyTableId FROM #Inserted
Detailed docs for OUTPUT clause: http://technet.microsoft.com/en-us/library/ms177564.aspx
-- table structure for example:
CREATE TABLE MyTable (
MyTableId int NOT NULL IDENTITY (1, 1),
MyTableColOne varchar(50) NOT NULL,
MyTableColTwo varchar(50) NOT NULL
)
##Identity is the old school way. Use SCOPE_IDENTITY() in all instances going forward. See MSDN for the repercussions of using ##IDENTITY (they're bad!).
SCOPE_IDENTITY is sufficient for single rows and is recommended except in cases where you need to see the result of an intermediate TRIGGER for some reason (why?).
For multiple rows, OUTPUT/OUTPUT INTO is your new best friend and alternative to re-finding the rows and inserting into another table.
There is another method available in SQL Server 2005 that is outlined in SQL in the Wild.
This will allow you to retrieve multiple identities after insert. Here's the code from the blog post:
Create Table #Testing (
id int identity,
somedate datetime default getdate()
)
insert into #Testing
output inserted.*
default values
A small correction to Godeke's answer:
It's not just triggers you need to worry about. Any kind of nested operation, such as stored procs, that causes identifiers to be created could change the value of ##IDENTITY.
Another vote for scope_identity...
Be carreful while using ##IDENTITY ...
http://dotnetgalactics.wordpress.com/2009/10/28/scope-identity-vs-identity/
How am I supposed to get the IDENTITY of an inserted row?
I know about ##IDENTITY and IDENT_CURRENT and SCOPE_IDENTITY, but don't understand the implications or impacts attached to each.
Can someone please explain the differences and when I would be using each?
##IDENTITY returns the last identity value generated for any table in the current session, across all scopes. You need to be careful here, since it's across scopes. You could get a value from a trigger, instead of your current statement.
SCOPE_IDENTITY() returns the last identity value generated for any table in the current session and the current scope. Generally what you want to use.
IDENT_CURRENT('tableName') returns the last identity value generated for a specific table in any session and any scope. This lets you specify which table you want the value from, in case the two above aren't quite what you need (very rare). Also, as #Guy Starbuck mentioned, "You could use this if you want to get the current IDENTITY value for a table that you have not inserted a record into."
The OUTPUT clause of the INSERT statement will let you access every row that was inserted via that statement. Since it's scoped to the specific statement, it's more straightforward than the other functions above. However, it's a little more verbose (you'll need to insert into a table variable/temp table and then query that) and it gives results even in an error scenario where the statement is rolled back. That said, if your query uses a parallel execution plan, this is the only guaranteed method for getting the identity (short of turning off parallelism). However, it is executed before triggers and cannot be used to return trigger-generated values.
I believe the safest and most accurate method of retrieving the inserted id would be using the output clause.
for example (taken from the following MSDN article)
USE AdventureWorks2008R2;
GO
DECLARE #MyTableVar table( NewScrapReasonID smallint,
Name varchar(50),
ModifiedDate datetime);
INSERT Production.ScrapReason
OUTPUT INSERTED.ScrapReasonID, INSERTED.Name, INSERTED.ModifiedDate
INTO #MyTableVar
VALUES (N'Operator error', GETDATE());
--Display the result set of the table variable.
SELECT NewScrapReasonID, Name, ModifiedDate FROM #MyTableVar;
--Display the result set of the table.
SELECT ScrapReasonID, Name, ModifiedDate
FROM Production.ScrapReason;
GO
I'm saying the same thing as the other guys, so everyone's correct, I'm just trying to make it more clear.
##IDENTITY returns the id of the last thing that was inserted by your client's connection to the database.
Most of the time this works fine, but sometimes a trigger will go and insert a new row that you don't know about, and you'll get the ID from this new row, instead of the one you want
SCOPE_IDENTITY() solves this problem. It returns the id of the last thing that you inserted in the SQL code you sent to the database. If triggers go and create extra rows, they won't cause the wrong value to get returned. Hooray
IDENT_CURRENT returns the last ID that was inserted by anyone. If some other app happens to insert another row at an unforunate time, you'll get the ID of that row instead of your one.
If you want to play it safe, always use SCOPE_IDENTITY(). If you stick with ##IDENTITY and someone decides to add a trigger later on, all your code will break.
The best (read: safest) way to get the identity of a newly-inserted row is by using the output clause:
create table TableWithIdentity
( IdentityColumnName int identity(1, 1) not null primary key,
... )
-- type of this table's column must match the type of the
-- identity column of the table you'll be inserting into
declare #IdentityOutput table ( ID int )
insert TableWithIdentity
( ... )
output inserted.IdentityColumnName into #IdentityOutput
values
( ... )
select #IdentityValue = (select ID from #IdentityOutput)
Add
SELECT CAST(scope_identity() AS int);
to the end of your insert sql statement, then
NewId = command.ExecuteScalar()
will retrieve it.
From MSDN
##IDENTITY, SCOPE_IDENTITY, and IDENT_CURRENT are similar functions in that they return the last value inserted into the IDENTITY column of a table.
##IDENTITY and SCOPE_IDENTITY will return the last identity value generated in any table in the current session. However, SCOPE_IDENTITY returns the value only within the current scope; ##IDENTITY is not limited to a specific scope.
IDENT_CURRENT is not limited by scope and session; it is limited to a specified table. IDENT_CURRENT returns the identity value generated for a specific table in any session and any scope. For more information, see IDENT_CURRENT.
IDENT_CURRENT is a function which takes a table as a argument.
##IDENTITY may return confusing result when you have an trigger on the table
SCOPE_IDENTITY is your hero most of the time.
When you use Entity Framework, it internally uses the OUTPUT technique to return the newly inserted ID value
DECLARE #generated_keys table([Id] uniqueidentifier)
INSERT INTO TurboEncabulators(StatorSlots)
OUTPUT inserted.TurboEncabulatorID INTO #generated_keys
VALUES('Malleable logarithmic casing');
SELECT t.[TurboEncabulatorID ]
FROM #generated_keys AS g
JOIN dbo.TurboEncabulators AS t
ON g.Id = t.TurboEncabulatorID
WHERE ##ROWCOUNT > 0
The output results are stored in a temporary table variable, joined back to the table, and return the row value out of the table.
Note: I have no idea why EF would inner join the ephemeral table back to the real table (under what circumstances would the two not match).
But that's what EF does.
This technique (OUTPUT) is only available on SQL Server 2008 or newer.
Edit - The reason for the join
The reason that Entity Framework joins back to the original table, rather than simply use the OUTPUT values is because EF also uses this technique to get the rowversion of a newly inserted row.
You can use optimistic concurrency in your entity framework models by using the Timestamp attribute: 🕗
public class TurboEncabulator
{
public String StatorSlots)
[Timestamp]
public byte[] RowVersion { get; set; }
}
When you do this, Entity Framework will need the rowversion of the newly inserted row:
DECLARE #generated_keys table([Id] uniqueidentifier)
INSERT INTO TurboEncabulators(StatorSlots)
OUTPUT inserted.TurboEncabulatorID INTO #generated_keys
VALUES('Malleable logarithmic casing');
SELECT t.[TurboEncabulatorID], t.[RowVersion]
FROM #generated_keys AS g
JOIN dbo.TurboEncabulators AS t
ON g.Id = t.TurboEncabulatorID
WHERE ##ROWCOUNT > 0
And in order to retrieve this Timetsamp you cannot use an OUTPUT clause.
That's because if there's a trigger on the table, any Timestamp you OUTPUT will be wrong:
Initial insert. Timestamp: 1
OUTPUT clause outputs timestamp: 1
trigger modifies row. Timestamp: 2
The returned timestamp will never be correct if you have a trigger on the table. So you must use a separate SELECT.
And even if you were willing to suffer the incorrect rowversion, the other reason to perform a separate SELECT is that you cannot OUTPUT a rowversion into a table variable:
DECLARE #generated_keys table([Id] uniqueidentifier, [Rowversion] timestamp)
INSERT INTO TurboEncabulators(StatorSlots)
OUTPUT inserted.TurboEncabulatorID, inserted.Rowversion INTO #generated_keys
VALUES('Malleable logarithmic casing');
The third reason to do it is for symmetry. When performing an UPDATE on a table with a trigger, you cannot use an OUTPUT clause. Trying do UPDATE with an OUTPUT is not supported, and will give an error:
Cannot use UPDATE with OUTPUT clause when a trigger is on the table
The only way to do it is with a follow-up SELECT statement:
UPDATE TurboEncabulators
SET StatorSlots = 'Lotus-O deltoid type'
WHERE ((TurboEncabulatorID = 1) AND (RowVersion = 792))
SELECT RowVersion
FROM TurboEncabulators
WHERE ##ROWCOUNT > 0 AND TurboEncabulatorID = 1
I can't speak to other versions of SQL Server, but in 2012, outputting directly works just fine. You don't need to bother with a temporary table.
INSERT INTO MyTable
OUTPUT INSERTED.ID
VALUES (...)
By the way, this technique also works when inserting multiple rows.
INSERT INTO MyTable
OUTPUT INSERTED.ID
VALUES
(...),
(...),
(...)
Output
ID
2
3
4
##IDENTITY is the last identity inserted using the current SQL Connection. This is a good value to return from an insert stored procedure, where you just need the identity inserted for your new record, and don't care if more rows were added afterward.
SCOPE_IDENTITY is the last identity inserted using the current SQL Connection, and in the current scope -- that is, if there was a second IDENTITY inserted based on a trigger after your insert, it would not be reflected in SCOPE_IDENTITY, only the insert you performed. Frankly, I have never had a reason to use this.
IDENT_CURRENT(tablename) is the last identity inserted regardless of connection or scope. You could use this if you want to get the current IDENTITY value for a table that you have not inserted a record into.
ALWAYS use scope_identity(), there's NEVER a need for anything else.
One other way to guarantee the identity of the rows you insert is to specify the identity values and use the SET IDENTITY_INSERT ON and then OFF. This guarantees you know exactly what the identity values are! As long as the values are not in use then you can insert these values into the identity column.
CREATE TABLE #foo
(
fooid INT IDENTITY NOT NULL,
fooname VARCHAR(20)
)
SELECT ##Identity AS [##Identity],
Scope_identity() AS [SCOPE_IDENTITY()],
Ident_current('#Foo') AS [IDENT_CURRENT]
SET IDENTITY_INSERT #foo ON
INSERT INTO #foo
(fooid,
fooname)
VALUES (1,
'one'),
(2,
'Two')
SET IDENTITY_INSERT #foo OFF
SELECT ##Identity AS [##Identity],
Scope_identity() AS [SCOPE_IDENTITY()],
Ident_current('#Foo') AS [IDENT_CURRENT]
INSERT INTO #foo
(fooname)
VALUES ('Three')
SELECT ##Identity AS [##Identity],
Scope_identity() AS [SCOPE_IDENTITY()],
Ident_current('#Foo') AS [IDENT_CURRENT]
-- YOU CAN INSERT
SET IDENTITY_INSERT #foo ON
INSERT INTO #foo
(fooid,
fooname)
VALUES (10,
'Ten'),
(11,
'Eleven')
SET IDENTITY_INSERT #foo OFF
SELECT ##Identity AS [##Identity],
Scope_identity() AS [SCOPE_IDENTITY()],
Ident_current('#Foo') AS [IDENT_CURRENT]
SELECT *
FROM #foo
This can be a very useful technique if you are loading data from another source or merging data from two databases etc.
Create a uuid and also insert it to a column. Then you can easily identify your row with the uuid. Thats the only 100% working solution you can implement. All the other solutions are too complicated or are not working in same edge cases.
E.g.:
1) Create row
INSERT INTO table (uuid, name, street, zip)
VALUES ('2f802845-447b-4caa-8783-2086a0a8d437', 'Peter', 'Mainstreet 7', '88888');
2) Get created row
SELECT * FROM table WHERE uuid='2f802845-447b-4caa-8783-2086a0a8d437';
Even though this is an older thread, there is a newer way to do this which avoids some of the pitfalls of the IDENTITY column in older versions of SQL Server, like gaps in the identity values after server reboots. Sequences are available in SQL Server 2016 and forward which is the newer way is to create a SEQUENCE object using TSQL. This allows you create your own numeric sequence object in SQL Server and control how it increments.
Here is an example:
CREATE SEQUENCE CountBy1
START WITH 1
INCREMENT BY 1 ;
GO
Then in TSQL you would do the following to get the next sequence ID:
SELECT NEXT VALUE FOR CountBy1 AS SequenceID
GO
Here are the links to CREATE SEQUENCE and NEXT VALUE FOR
Complete solution in SQL and ADO.NET
const string sql = "INSERT INTO [Table1] (...) OUTPUT INSERTED.Id VALUES (...)";
using var command = connection.CreateCommand();
command.CommandText = sql;
var outputIdParameter = new SqlParameter("#Id", SqlDbType.Int) { Direction = ParameterDirection.Output };
command.Parameters.Add(outputIdParameter);
await connection.OpenAsync();
var outputId= await command.ExecuteScalarAsync();
await connection.CloseAsync();
int id = Convert.ToInt32(outputId);
After Your Insert Statement you need to add this. And Make sure about the table name where data is inserting.You will get current row no where row affected just now by your insert statement.
IDENT_CURRENT('tableName')