Inserting to a table with an identity column - sql

I am trying to insert a row to a table with an identity column and three "normal" columns using entity framework in wpf.
however i got this error message:
Cannot insert explicit value for identity column in table 'MyTable' when IDENTITY_INSERT is set to OFF
here is my code snippet, trying to add to the user table who has name, surname, age and userID(identity) column:
var newuser = new User();
newuser.SurName = surNameTextBox.Text;
newuser.Name = nameTextBox.Text;
newuser.Age = Int32.Parse(ageTextBox.Text);
context.AddToUsers(newuser);
context.SaveChanges();
Can anyone help me on solving this problem?

I'm not familiar with entity-framework, but for the curious this is the MS SQL command for enabling an insert on an identity column:
SET IDENTITY_INSERT tablename ON
I agree with Wonko to Sane, the problem is almost certainly in the AddToUsers method.

Identity columns indeed update themselves - that is their purpose.
If this is the only code that you are using to update the User, then I would look at (or post) the AddToUsers method in the DataContext.

Related

Insert into table of multi tenancy project

I need to update(or insert, I dont do a lot of sql work so I dont know which one I really need) some data in our database but its a multi tenant db and I am having trouble specifying which tenant I want to insert into. The current value in the column for this table is NULL. I need to add some data into that column
I need to do something like:
INSERT INTO Tenant(Address1) Values('5800 Nova Dr') WHERE TenantId='2'
Its the "WHERE" part that Azure Data Studio is not liking. Everything I found online was about inserting from another table. Any help would be appreciated!
you can use insert syntax to add a new row if you know the tenantId number
INSERT INTO Tenant(TenantId, Address1) Values(2, '5800 Nova Dr');
use update syntax if you have already prefilled the table row with null values
UPDATE Tenant SET Address1='5800 Nova Dr' WHERE TenantId=2
I think this should work if your table have an autoincrement value as primary key, otherwise you need to specify also the TenantID.
You can't use WHERE in insert, because is a new row.
INSERT INTO Tenant(Address1) values ('5800 Nova Dr')
If you want to update the value of already existing raw you can use
UPDATE Tenant SET Address1 = "5800 Nova Dr" WHERE Address1 like = '5800 Nova Dr'
UPDATE Tenant SET Address1='5800 Nova Dr' WHERE TenantId='2'

Should required field have a Null Constraint?

Few new columns needs to be added to an existing table in sql server 2008 R2. New columns are like required field, user can't add a new row without passing any values to those new columns.
In .Net code, there is already a method to validate values before inserting a new record.
Is there an advantage of adding a Not Null constraint on new columns?
If a column should not allow the value NULL then yes, you should most definitely declare NOT NULL as part of it's definition. Just because the application handles it now doesn't mean it will later, or that someone will (foolishly) run an INSERT or UPDATE statement on your table(s) with SET ColumnName = NULL.

SQL simplist way to update an INT identity column

I have a column called fixedID, and it's current Value = 2, I want to update this value to be 42. What is the best way to do this. I would like to do this modification as simply as possible. However, if I could do this while doing an select insert that would be fantastic also.
update tblFixedId
set FixedId = (FixedId + 400)
possible to change the value here?
Select * INTO mynewTable from myOldertable
Identity columns are not updatable in SQL Server.
The only way of doing this as an actual UPDATE rather than a DELETE ... INSERT would be to use ALTER TABLE ... SWITCH to mark the column as no longer an IDENTITY column, do the UPDATE then ALTER TABLE ... SWITCH again to re-mark the column as IDENTITY (For example code the first way round see the workarounds on this Connect Item and for the second way here).
Note that in the common scenario that the identity column is the clustered index key the Update will likely be implemented as an INSERT ... DELETE anyway.

SQL Server - Return value after INSERT

I'm trying to get a the key-value back after an INSERT-statement.
Example:
I've got a table with the attributes name and id. id is a generated value.
INSERT INTO table (name) VALUES('bob');
Now I want to get the id back in the same step. How is this done?
We're using Microsoft SQL Server 2008.
No need for a separate SELECT...
INSERT INTO table (name)
OUTPUT Inserted.ID
VALUES('bob');
This works for non-IDENTITY columns (such as GUIDs) too
Use SCOPE_IDENTITY() to get the new ID value
INSERT INTO table (name) VALUES('bob');
SELECT SCOPE_IDENTITY()
http://msdn.microsoft.com/en-us/library/ms190315.aspx
INSERT INTO files (title) VALUES ('whatever');
SELECT * FROM files WHERE id = SCOPE_IDENTITY();
Is the safest bet since there is a known issue with OUTPUT Clause conflict on tables with triggers. Makes this quite unreliable as even if your table doesn't currently have any triggers - someone adding one down the line will break your application. Time Bomb sort of behaviour.
See msdn article for deeper explanation:
http://blogs.msdn.com/b/sqlprogrammability/archive/2008/07/11/update-with-output-clause-triggers-and-sqlmoreresults.aspx
Entity Framework performs something similar to gbn's answer:
DECLARE #generated_keys table([Id] uniqueidentifier)
INSERT INTO Customers(FirstName)
OUTPUT inserted.CustomerID INTO #generated_keys
VALUES('bob');
SELECT t.[CustomerID]
FROM #generated_keys AS g
JOIN dbo.Customers AS t
ON g.Id = t.CustomerID
WHERE ##ROWCOUNT > 0
The output results are stored in a temporary table variable, and then selected back to the client. Have to be aware of the gotcha:
inserts can generate more than one row, so the variable can hold more than one row, so you can be returned more than one ID
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.
SQL Server 2008 or newer only. If it's 2005 then you're out of luck.
There are many ways to exit after insert
When you insert data into a table, you can use the OUTPUT clause to
return a copy of the data that’s been inserted into the table. The
OUTPUT clause takes two basic forms: OUTPUT and OUTPUT INTO. Use the
OUTPUT form if you want to return the data to the calling application.
Use the OUTPUT INTO form if you want to return the data to a table or
a table variable.
DECLARE #MyTableVar TABLE (id INT,NAME NVARCHAR(50));
INSERT INTO tableName
(
NAME,....
)OUTPUT INSERTED.id,INSERTED.Name INTO #MyTableVar
VALUES
(
'test',...
)
IDENT_CURRENT: It returns the last identity created for a particular table or view in any session.
SELECT IDENT_CURRENT('tableName') AS [IDENT_CURRENT]
SCOPE_IDENTITY: It returns the last identity from a same session and the same scope. A scope is a stored procedure/trigger etc.
SELECT SCOPE_IDENTITY() AS [SCOPE_IDENTITY];
##IDENTITY: It returns the last identity from the same session.
SELECT ##IDENTITY AS [##IDENTITY];
##IDENTITY Is a system function that returns the last-inserted identity value.
There are multiple ways to get the last inserted ID after insert command.
##IDENTITY : It returns the last Identity value generated on a Connection in current session, regardless of Table and the scope of statement that produced the value
SCOPE_IDENTITY(): It returns the last identity value generated by the insert statement in the current scope in the current connection regardless of the table.
IDENT_CURRENT(‘TABLENAME’) : It returns the last identity value generated on the specified table regardless of Any connection, session or scope. IDENT_CURRENT is not limited by scope and session; it is limited to a specified table.
Now it seems more difficult to decide which one will be exact match for my requirement.
I mostly prefer SCOPE_IDENTITY().
If you use select SCOPE_IDENTITY() along with TableName in insert statement, you will get the exact result as per your expectation.
Source : CodoBee
The best and most sure solution is using SCOPE_IDENTITY().
Just you have to get the scope identity after every insert and save it in a variable because you can call two insert in the same scope.
ident_current and ##identity may be they work but they are not safe scope. You can have issues in a big application
declare #duplicataId int
select #duplicataId = (SELECT SCOPE_IDENTITY())
More detail is here Microsoft docs
You can use scope_identity() to select the ID of the row you just inserted into a variable then just select whatever columns you want from that table where the id = the identity you got from scope_identity()
See here for the MSDN info http://msdn.microsoft.com/en-us/library/ms190315.aspx
Recommend to use SCOPE_IDENTITY() to get the new ID value, But NOT use "OUTPUT Inserted.ID"
If the insert statement throw exception, I except it throw it directly. But "OUTPUT Inserted.ID" will return 0, which maybe not as expected.
This is how I use OUTPUT INSERTED, when inserting to a table that uses ID as identity column in SQL Server:
'myConn is the ADO connection, RS a recordset and ID an integer
Set RS=myConn.Execute("INSERT INTO M2_VOTELIST(PRODUCER_ID,TITLE,TIMEU) OUTPUT INSERTED.ID VALUES ('Gator','Test',GETDATE())")
ID=RS(0)
You can append a select statement to your insert statement.
Integer myInt =
Insert into table1 (FName) values('Fred'); Select Scope_Identity();
This will return a value of the identity when executed scaler.
* Parameter order in the connection string is sometimes important. * The Provider parameter's location can break the recordset cursor after adding a row. We saw this behavior with the SQLOLEDB provider.
After a row is added, the row fields are not available, UNLESS the Provider is specified as the first parameter in the connection string. When the provider is anywhere in the connection string except as the first parameter, the newly inserted row fields are not available. When we moved the the Provider to the first parameter, the row fields magically appeared.
After doing an insert into a table with an identity column, you can reference ##IDENTITY to get the value:
http://msdn.microsoft.com/en-us/library/aa933167%28v=sql.80%29.aspx

Is there an easy way to add a custom migration script to SQL Compare scripts?

At my work we are currently having some serious pains pushing our database changes across environments. The issue starts to show up when we create a new non-nullable column on an existing table. The script that SQL Compare generates creates the column as non-nullable, so it will always fail. I was hoping that there was some alternative to having to manually edit the script. Is there any way to get around this? If not, how do you guys handle it?
Create a table:
create table #bingo ( id int )
Add a value:
insert into #bingo values (1)
Add a new column:
alter table #bingo add userid int
Populate the new column:
update #bingo set userid = 1 where id = 1
Change the new column to not nullable:
alter table #bingo alter column userid int not null
You would have to manually edit the RedGate Sql Compare to make it work like this.
How do you plan on filling the NOT NULL column? I don't see how SQL Compare could really come up with a solution since it has no way of knowing how you would fill it.
You could create the column with a DEFAULT, then simply add an update statement at the end of the generated scripts to properly update the column if you have some source for the values.
add a default onto the new not null column
when creating a new not null column, what value do all the existing rows get? If you don't know, make the column nullable.