I have a table in SQL server 2008.
I need a column that until now wasn't necessary, not to allow NULL anymore, without droping the table.
I tried to do something like this:
ALTER TABLE [Sessions] ALTER COLUMN region_id NOT NULL;
EDIT: It was a small syntax error. solved.
You have to specify the data type as well when you alter a column:
ALTER TABLE [Sessions] ALTER COLUMN region_id int /* ? */ NOT NULL;
you are missing datatype.
ALTER TABLE [Sessions] ALTER COLUMN region_id int NOT NULL;
You have to first set all values that are NULL to a non NULL value:
UPDATE [Sessions]
SET region_id=-1
WHERE region_id IS NULL
Instead of -1 you should choose something that would represent the formerly NULL values so you may distinguish them.
To get away with saving prevention you may go on:
Tools>Options>Designers> and unclick Prevent Saving Changes that require table re-creation
First off to save table chances like this you need to either script the changes, or when saving from the UI, you need to set SSMS to drop and recreate table for you. To do this;
Go to Tools
Options
Designers
UNTICK prevent saving changes that require table re-creations.
If you script the changes, you will need to first alter the table, and add a new column allowing nulls. Then update the column and remove nulls and then after you will be able to set the column to NOT NULL.
If you follow these steps you will solve your issue.
Related
I have a PostgreSQL (9.0) database with a column card_id which is currently of type integer
I need to change this to type text
What is the most best way to achieve this?
The only solution I can find involves creating a temporary column, dropping the original then renaming, I thought they might be a better method??
Have you tried what the fine manual suggests:
ALTER TABLE table ALTER COLUMN anycol TYPE anytype;
Depending on the current and the new type you may need to add USING ... to this statement.
But in your specific case that should not be necessary I believe.
ALTER TABLE table ALTER COLUMN card_id SET DATA TYPE text;
I am trying to add a column to a tsql table, i do this using SMO in c#. Altering the table is fine but i want to set the column to have a value. The table contains 650 million rows and the update query is taking over a day and a half to run.
Update [TempDatabase].[dbo].[table1] set RawSource = 'DTP'
This is the query I am running above.
Can anyone think of a more efficient way of doing this?
Thanks in advance.
Sometimes, it is more efficient to copy the table with the new value and re-create the table in a single command. Also, you might want to be sure that you have minimal logging for these operations.
Probably the best solution is to use a default value when you create the column:
alter table table1 add RawSource varchar(255) not null default 'DTP';
If you don't want the default moving forward, you can remove it after the column is added.
Another method uses computed columns, but basically does the same thing:
alter table table1 add _RawSource varchar(255);
alter table1 add RawSource as (coalesce(_RawSource, 'DTP'));
at the time of addition of column to table only we can set a default value which will applies for all rows
Note:U should keep not null compulsory because if not all rows are applicable with nulls
alter table table_name
add row_source nvarchar(5) not null default(N'DTP')
I'm looking at a sql server table, and one of the columns seems to have been setup to be of type INT NULL when it's really better off as a BIT NOT NULL.
Is there an easy formula or shortcut for switching the type?
My current strategy is:
add new temp column
populate with data based on old column contents
drop old column and constraints
rename new column to old column name
add constraints based on new column
this seems complicated but, really, should be automatable - so i'm wondering if anyone's automated it yet.
Update MyTable set MyColumn = 0 where MyColumn is null
Assuming you want null to be false
Alter table MyTable alter column MyColumn bit not null
Will do the job, given all non-zero values are to be treated as true.
Course you were going to backup before you did any of this weren't you. :)
I have database and some text fields are CLOB type, I need to change most of these into VARCHAR2.
Have tried to do that using SQL Developer tool, by clicking edit on table, but get error like this one:
The following SQL statement failed:
ALTER TABLE TBL_PEOPLE MODIFY (PERSON VARCHAR2(150) )
Want to ask, how can this change be done
You can't, directly. The code you tried will have got an `ORA-22859, presumably. (It's helpful to show the actual errors you get, of course).
You'll need to add a new varchar2 column; copy the data across - or a substring of it if it might be larger than the new column you're creating; drop the clob column. You can rename the columns so it looks fairly transparent.
As in this SQL Fiddle:
alter table tbl_people rename column person to clob_person;
alter table tbl_people add (person varchar2(150));
update tbl_people set person = clob_person;
alter table tbl_people drop column clob_person;
Obviously don't drop the old column until you're sure the data has copied without errors. Also take into account any constraints, indexes, etc. that might exist in the old column; they will need to be recreated. And anything that references the old column will have been invalidated - generally procedures will recompile themselves on next use.
So be careful, test it first, and plan some down time.
ALTER TABLE tablename ADD (FIELD_LIST_TEMP VARCHAR2);
UPDATE tablename SET FIELD_LIST_TEMP = FIELD_LIST;
ALTER TABLE tablename DROP COLUMN FIELD_LIST;
ALTER TABLE tablename RENAME COLUMN FIELD_LIST_TEMP TO FIELD_LIST;
Here FIELD_LIST existing column which is defined it as CLOB. With above query it will change from CLOB to VARCHAR2.
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.