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.
Related
I have a vb.net application where datagridview is databound to sql table at design time(with table adapter and dataset). All I wanted is to get newly added row's Primary key(int) when i add new row to it. I have searched, but it's showing sql commands like below:
INSERT INTO #Customers
(Name)
VALUES ('Customer 1')
SELECT SCOPE_IDENTITY()
so using scope_identity(). But is there any way I can do it with adapter(or dataset) in vb.net or same command can be given though adapter or similar ?
Thanks in advance!
try this!
SCOPE_IDENTITY() will give you the last identity value inserted into any table directly within the current scope (scope = batch, stored procedure, etc. but not within, say, a trigger that was fired by the current scope)
Use the OUTPUT clause if you are inserting multiple rows and need to retrieve the set of IDs that were generated.
INSERT #a(x) OUTPUT inserted.identity_column VALUES('b'),('c');
--
result will be
1
2
I have a table where i have a column called student id and in that column i want to insert like SN + userid.But i know how to create a new column and do this but i want to add this to an existing column whenever a user is inserted.
ALTER TABLE [dbo].[Profile_Master]
Add [new] as ('SN'+CONVERT([varchar] (10),[UserId],(0)))
In SQL Server you can use triggers to do this:
http://msdn.microsoft.com/en-us/library/aa258254%28v=sql.80%29.aspx
Your solution is already compliant to your requirements: you are creating a computed column.
Thus, it will work for existing records and for new ones created in the future.
In Sql Server 2008, I have a table that is filled by a data provider application.
I want to keep an "INSERT_DATE" column on table, so that I can know the date the record is inserted.
In order to do this, I defined a default constraint on INSERT_DATE column which puts GETDATE() by default.
However, I don't want this column value to be overwritten by data provider application.
So, how can I disable insert into INSERT_DATE column?
(I cannot use computed column. Because Clustered Index uses INSERT_DATE field)
You could use an After Insert trigger. That way, whatever is inserted into that column for an inserted row you could update to the current date/time.
You probably don't want the column updates as well when the row is subsequently updated.
Your best bet is to use a trigger. You might not be able to throw an error if the application provides a value but at least you will be able to set it right by skipping the column in the insert you specify in your trigger.
I want to add or update columns using alter table if i am adding a new column i want show error. I am using the code below
alter table Personal_Details alter columns DOB datetime
if i uncheck the NULL to not NULL then it will shows column does not allow nulls; update fails;
i want to insert the fields in between columns not at end.
Plese fix my bug,
Thanks in advance.
The position of the column in the table declaration has nothing to do with its being NULL or NOT NULL.
If you are adding a column (of any type) which you want to be NOT NULL, i.e. you want to prohibit NULL values in that column, and the table already contains some rows, you must also provide some default value. For example:
ALTER TABLE Personal_Details
ADD COLUMN DOB datetime NOT NULL DEFAULT (GETDATE())
Otherwise the engine will attempt to add that column with NULLs as its values, which will violate the NOT NULL property, and the change, therefore, will be reverted.
Basically, the same applies when you want to set an existing column's NOT NULL property on while the column already contains NULLs. But in this case you must explicitly eliminate the NULLs before the change by either replacing them with values or removing the respective rows.
Source:
ALTER TABLE (Transact-SQL). (The particular section related to your problem is just above this code snippet.)
1)For ur adding column with not null problem
Use
ALTER TABLE Personal_Details ADD COLUMN DOB datetime NULL
Update the DOB column with the required dates and make sure there is no null in the column
then alter the column using
ALTER TABLE Personal_Details ALTER COLUMN DOB datetime not NULL
2)For your column going to the end problem...
you should not be worried...the order in which the columns are arranged doesnt matter...unless u are using a pathetic way of accessing data by column order..in which case again..u should stop accessing it by column order...
If the column order really matters you can change it using design option in the sql management table(rightclick on table >design and drag the column to its required place.)
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.