I use this code to check if an element of the new entry is equal to an element of previously inserted data.
CREATE TRIGGER trig1 ON Table1
AFTER INSERT
AS
DECLARE trigcursor CURSOR FOR
SELECT Name FROM INSERTED
DECLARE #Name1 varchar(80)
OPEN trigcursor;
FETCH NEXT FROM trigcursor INTO #Name1
WHILE ##FETCH_STATUS = 0
BEGIN
IF EXISTS(SELECT * FROM Table1 WHERE Name= #Name1)
BEGIN
...
END
FETCH NEXT FROM trigcursor INTO #Name1
END
The problem is that for some reason the new entry exists also in the table Table1, not only in INSERTED. So the condition is always true. Can you help me why this happens? Is there a way to retrieve only the initial table without the new entry in it? Thanks!
Your trigger is AFTER INSERT on table Table1. It should be BEFORE INSERT if you expect not to find the record in the table.
Alternative: use INSTEAD OF INSERT trigger.
OR
Add another column that accepts null. Make it a number column so that it will be fast. Do not insert any value in it on the insert. Then, in the AFTER INSERT TRIGGER, the rows that have that column empty are the new ones. The ones that have the column filled with something are the old ones.
Then update empty columns with value.
eg: add column mark
After insert, look for the name:
SELECT * FROM Table1 WHERE Name= #Name1 and mark is not null
Once you found out whether or not it existed before, update everything with something:
update table1 set mark = 1 where mark is null
I want to write trigger. When there is an entry in table1, table2 should get inserted with same values. And in some field in table1 is updated then respective field must get updated in table2. How can I know whether value is inserted or updated?
I am using inserted to insert value.
Please guide me.
Here is how you will know whether a value is inserted or updated in a trigger like this:
on INSERT, the inserted dynamic table is populated with the new values
on UPDATE, the inserted dynamic table is populated with the new values of the records that were updated, and the deleted dynamic table is poulated with the old values of the records that were updated
So basically, if the deleted table contains the id (assuming you have an id column) as in the inserted table, you can be assured that it was an UPDATE that caused the trigger. If the deleted table is empty, conversely, it was an INSERT.
use this trigger to solve your problem..
create TRIGGER [dbo].[insert_Assets_Tran]
ON [dbo].[AssetMaster]
AFTER INSERT , UPDATE
AS BEGIN
DECLARE #isnum TINYINT;
SELECT #isnum = COUNT(*) FROM inserted;
IF (#isnum = 1)
INSERT INTO AssetTransaction
select [AssetId],[Brandname],[SrNo],[Modelno],[Processor],[Ram],[Hdd],[Display],[Os],[Office],[Purchasedt]
,[Expirydt],[Vendor],[VendorAMC],[Typename],[LocationName],[Empid],[CreatedBy],[CreatedOn],[ModifiedBy]
,[ModifiedOn],[Remark],[AssetStatus],[Category],[Oylstartdt],[Oylenddt],[Configuration]
,[AStatus],[Tassign]
FROM inserted;
ELSE
RAISERROR('some fields not supplied', 16, 1)
WITH SETERROR;
END
After much research I am a little confused by which identity tracker I should use in sql.
From what I understand scope_identity will give me the last id updated from any table and ident_current will will return the last id from a specified table.
So given that information it would seem to me the best version to use (if you know which table you will be updating) is ident_current. Yet, upon reading it seems most people prefer to use scope_identity. What is the reasoning behind this and is there a flaw in my logic?
In that case you need to write the table name, what happens if you decide to change the table name? You then also must not forget to update your code to reflect that. I always use SCOPE_IDENTITY unless I need the ID from the insert that happens in a trigger then I will use ##IDENTITY
Also the bigger difference is that IDENT_CURRENT will give you the identity from another process that did the insert (in other words last generated identity value from any user)
so if you do an insert and then someone does an insert before you do a SELECT IDENT_CURRENT you will get that other person's identity value
See also 6 Different Ways To Get The Current Identity Value which has some code explaining what happens when you put triggers on the table
From what I've read scope_identity() should be the right answer, however it looks like there is a bug in SQL 2005 and SQL 2008 that can come into play if your insert results in a parallel query plan.
Take a look at the following articles for more details:
##IDENTITY vs SCOPE_IDENTITY() vs IDENT_CURRENT - Retrieve Last Inserted Identity of Record
Article: Six reasons you should be nervous about parallelism
See section titled: 1. #328811, "SCOPE_IDENTITY() sometimes returns incorrect value"
See this blogpost for your answer in detail. Scope_identity will never return identities due to inserts done by triggers. It wont be a great idea to use ident_current in a world of change where tablenames are changed..like in a dev env.
/*
* IDENT_CURRENT returns the last identity value generated for a specific table in any session and any scope.
* ##IDENTITY returns the last identity value generated for any table in the current session, across all scopes.
* SCOPE_IDENTITY returns the last identity value generated for any table in the current session and the current scope.
*/
IF OBJECT_ID(N't6', N'U') IS NOT NULL
DROP TABLE t6 ;
GO
IF OBJECT_ID(N't7', N'U') IS NOT NULL
DROP TABLE t7 ;
GO
CREATE TABLE t6 (id INT IDENTITY) ;
CREATE TABLE t7
(
id INT IDENTITY(100, 1)
) ;
GO
CREATE TRIGGER t6ins ON t6
FOR INSERT
AS
BEGIN
INSERT t7
DEFAULT VALUES
END ;
GO
--End of trigger definition
SELECT id
FROM t6 ;
--IDs empty.
SELECT id
FROM t7 ;
--ID is empty.
--Do the following in Session 1
INSERT t6
DEFAULT VALUES ;
SELECT ##IDENTITY ;
/*Returns the value 100. This was inserted by the trigger.*/
SELECT SCOPE_IDENTITY() ;
/* Returns the value 1. This was inserted by the
INSERT statement two statements before this query.*/
SELECT IDENT_CURRENT('t7') ;
/* Returns 100, the value inserted into t7, that is in the trigger.*/
SELECT IDENT_CURRENT('t6') ;
/* Returns 1, the value inserted into t6 four statements before this query.*/
-- Do the following in Session 2.
SELECT ##IDENTITY ;
/* Returns NULL because there has been no INSERT action
up to this point in this session.*/
SELECT SCOPE_IDENTITY() ;
/* Returns NULL because there has been no INSERT action
up to this point in this scope in this session.*/
SELECT IDENT_CURRENT('t7') ;
/* Returns 100, the last value inserted into t7.*/
The theory says: To be aware of race conditions and to do not care about inserts inside triggers, you should be using SCOPE_IDENTITY() BUT ... there are know bugs on SCOPE_IDENTITY() (and ##IDENTITY) as is mentioned and linked on other anwsers. Here are the workarounds from Microsoft that takes into account this bugs.
Below the most relevant part from the article. It uses output insert's clause:
DECLARE #MyNewIdentityValues table(myidvalues int)
declare #A table (ID int primary key)
insert into #A values (1)
declare #B table (ID int primary key identity(1,1), B int not null)
insert into #B values (1)
select
[RowCount] = ##RowCount,
[##IDENTITY] = ##IDENTITY,
[SCOPE_IDENTITY] = SCOPE_IDENTITY()
set statistics profile on
insert into _ddr_T
output inserted.ID into #MyNewIdentityValues
select
b.ID
from #A a
left join #B b on b.ID = 1
left join #B b2 on b2.B = -1
left join _ddr_T t on t.T = -1
where not exists (select * from _ddr_T t2 where t2.ID = -1)
set statistics profile off
select
[RowCount] = ##RowCount,
[##IDENTITY] = ##IDENTITY,
[SCOPE_IDENTITY] = SCOPE_IDENTITY(),
[IDENT_CURRENT] = IDENT_CURRENT('_ddr_T')
select * from #MyNewIdentityValues
go
SELECT IDENT_CURRENT -- as you said will give you the table specific last inserted identity value. There are issues associated with this, one the user need to have permission to see the metadata otherwise it returns NULL and second you are hardcoding the name of the table , which will cause a problem in case the table name changes.
The best practice is to use Scope_Identity together with a variable ...Look the following example
DECLARE #myFirstTableID INT
DECLARE #mySecondTableID INT
INSERT INTO MYFirstTable (....) VALUES (.....)
SELECT #myFirstTableID =SCOPE_IDENTITY()
INSERT INTO MYSecondTable () VALUES (.....)
SELECT #mySecondTableID=SCOPE_IDENTITY()
Thus by making use of variable and scope_identity next to the insert statement of interest, you can make sure that you are getting the right identity from the right table.
Enjoy
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')