using replication in sql srv causes the addition of this guid field, it also adds a value to it
but when i insert new records to the db, i have to give somthing or the guid field
it should be like aaaaa-aaa-something and unique!!
this is a problem for me , how am i supposed to do this keeping it unique every time?
should sql srv automatically add some yhing?
The ROWGUIDCOL added by Merge Replication should be populated with... guids:
ROWGUIDCOL does not enforce uniqueness
of the values that are stored in the
column and does not automatically
generate values for new rows that are
inserted into the table. To generate
unique values for each column, either
use the NEWID function on INSERT
statements or specify the NEWID
function as the default for the
column.
Related
is that possible to do a computed column without affecting existing data?
I have a unique index column named
"BookingNo"
For newly insert Column I want it to be following this format
(format([CreationTime],'yyMMddHHmmssff'))
I tried used Computed Column but it modified all my existing data.
my existing BookingNo format was
201800123
Is there anyway to generate via database? Or we have insert via code?
You could just add a default constraint:
ALTER TABLE TableName
ADD CONSTRAINT DF_BookingNo DEFAULT(format(SYSDATETIME(),'yyMMddHHmmssff'))
FOR BookingNo
This way you will get the value only for newly created rows.
Please note that if this column has a unique constraint on it some inserts might fail if they are executed at the same time.
Is it possible to only alter a table to make an existing column a serial auto generated key, without adding a new column? Sorry if this question is a bit newbie-ish for PostgreSQL, I'm more a SQL Server person but moving to PostgreSQL..
In a nut shell the program will copying an existing SQL Server database into PostgreSQL. With the desire to have a mirrored DB in PostgreSQL as the source from SQL Server with the only caveat one may selectively include/exclude any table or column as desired, or do everything...
Given the process copies all values, thought one should be able create the keys after the copy has finished just as one may do in SQL Server. Thought PostgreSQL would have a comparable methods as SQL Server's SET INSERT_IDENTITY [ON|OFF] so one may override the auto generated key with a desired value. Not seeing an equivalent in PostgreSQL. So my fallback is to create the mirrored records in Postgres without keys any keys and then alter the tables. But it seems to fix up the table as desired one has create a new column, but doing this break or cause a headache fixing up the RI for PK/FK relationships.
Any suggestions? Thanks in advance.
In PostgreSQL, the auto-generated key is always overridden if you insert an explicit value for it. If you don't specify a value (omit the column), or specify the keyword DEFAULT, a generated key is used.
Given table
CREATE TABLE t1 (id serial primary key, dat text);
then both these will get a generated key from sequence t1_id_seq:
INSERT INTO t1 (dat) VALUES ('fred');
INSERT INTO t1 (id, dat) VALUES (DEFAULT, 'bob');
This will instead provide its own value:
INSERT INTO t1 (id, dat) VALUES (42, 'joe');
You are responsible for ensuring that the provided value doesn't conflict with existing data, or with future values the identity sequence will generate. PostgreSQL will not notice that you manually inserted a row with id 42 and skip when its own sequence counter gets to that point.
Usually what you do is load with provided values, then reset the sequence to the max of all keys already in the table, so it keeps counting from there for new local inserts.
I have a table filled with data and one of the columns - TrackingNumber - is an integer value. I have gotten a request to change it to auto-increment and to have it start the identity seed at 1000000. I know that I cannot alter a column to be an identity column in an existing table with data, so I have two options: either create an entirely new table and then move data from the old table into that new table or add an new identity column and update it with data from the old column.
The problem is that I need to retain all the existing values in column TrackingNumber. I have tried the following:
1) ALTER TABLE [dbo].[Table1]
ADD [TrackingNumber2] [bigint] IDENTITY (1000000, 1) NOT NULL
2) UPDATE [dbo].[Table1]
SET [TrackingNumber2]=[TrackingNumber]
3) ALTER TABLE [dbo].[Table1]
DROP COLUMN [TrackingNumber]
GO
4) EXEC sp_rename 'Table1.TrackingNumber2', 'TrackingNumber','COLUMN'
I got an error on step 2 - Updating new column with the value from the old column: "Cannot update identity column 'TrackingNumber2'"
Can anyone recommend a workaround?
You just need to set identity_insert on for this table so you can update the values. Make sure you turn it back off when you complete the update. :)
https://msdn.microsoft.com/en-us/library/ms188059.aspx
Are you sure you need to use an identity column? There are alternatives. For example, since SQL Server 2012 (and azure, too), there are these things called sequences. You can define a sequence to start at any number you like:
create sequence dbo.TrackingSequence
as int
start with 1000000
increment by 1
no maxvalue
no cycle
no cache
Then, you can alter the table such that the default value for the column in question defaults from the sequence:
alter table dbo.MyTable
add constraint [MyTable.TrackingNumber.Default.TrackingSequence]
default( next value for dbo.TrackingSequence ) for TrackingNumber
(If the column already has a default value, you need to remove that first - in a separate statement.)
A sequence works a lot like an identity, but you don't have to disrupt existing values or the column definition per se.
The only trick is to remember to not specify the value for TrackingNumber, and let the DB do its thing.
Sequences are cool in that you can have one sequence that is used by multiple tables, giving you somewhat shorter db-wide unique IDs than alternatives in the past. For such an application, you'd probably be better off with a bigint column - or know that the tables in question aren't going to be terribly long.
I ended up creating a new table and moving data in there
Good day
I have a situation where two users are saving data to the same database and there are primary key conflicts.
Is it possible to write a stored procedure or trigger which will generate a unique identity by adding two columns.
For instance: I have table2 related to table1 by Table1ID. Increment and seed is 1 for both.
If I had to add a row to table2 I would like the autogenerated ID number to be added to a text column thereby making it unique. So the ID would be something like JoeSoap5.
If you want to generated something unique you can use the build-in function "NEWID()". Type and executed the following code:
SELECT NEWID()
If you need to insert record in second table when record in your first table is inserted, is is possible to implement this using TRIGGERS. In your case you can use "AFTER INSERT TRIGGER" or "BEFORE INSERT TRIGGER" - generally this will be a piece of code that will be executed AFTER/BEFORE row in your first table is inserted.
You don't specify your SQL Server version.
SQL 2012 introduces the concept of a sequence - http://msdn.microsoft.com/en-us/library/ff878091.aspx - which would allow you to do just what you want.
We have a production table with 770 million rows and change. We want(/need?) to change the Primary ID column from int to bigint to allow for future growth (and to avoid the sudden stop when the 32bit integer space is exhausted)
Experiments in DEV have shown that this is not as simple as altering the column as we would need to drop the index and then re-create it. So far in DEV (which is a bit humbler than PROD) the dropping of the index has not finished after 1 and a half hours. This table is hit 24/7 and having it offline for such a long time is not an option.
Has anyone else had to deal with a similar situation? How did you get it done?
Are there alternatives?
Edit: Additional Info:
The Primary key is clustered.
You could attempt a staged approach.
Create a new bigint column
Create an insert trigger to keep new entries in sync with the 2 columns
Execute an update to populate all the empty values in the bigint column with the converted value
Change the primary index on the table from your old id column to the new one
Point any FK's and queries to use the new column
Change the new column to become your identity column and remove the insert trigger from #2
Delete the old ID column
You should end up spreading the pain out over these 7 steps instead of hitting it all at once.
Create a parallel table with the longer data type for new rows and UNION the results?
What I had to do was copy the data into a new table with the desired structure (primary/clustered key only, non-clustered/FK once complete). If you don't have the room, you could bcp out the data and back in. You may need an application outage to make this happen.
What doesn't work: alter table Orderhistory alter column ID bigint because of the primary key. Don't drop the key and alter column as you will just fill your log file and take much longer than copy/bcp.
Never use the SSMS tools designer to change a column property, it copies table into temp table then does a rename once done. Lookup the alter table alter column syntax and use it and possibly defrag once complete if you modified a column wider that sits in middle of table.