I have two database one local and other in production.
In one of them I have column IdNivelDominio without FK but if I open Constraints folder and I have something like:
DF_EvaluacionDetalleCompetenciasFuncionales_IdNivelDominio
So I want to reply this field into my another database as:
ALTER TABLE Reclutamiento.EvaluacionDetalleCompetenciasFuncionales
ADD IdNivelDominio INT NOT NULL;
But I get error:
ALTER TABLE only allows columns to be added that can contain nulls, or
have a DEFAULT definition specified, or the column being added is an
identity or timestamp column, or alternatively if none of the previous
conditions are satisfied the table must be empty to allow addition of
this column. Column 'IdNivelDominio' cannot be added to non-empty
table 'EvaluacionDetalleCompetenciasFuncionales' because it does not
satisfy these conditions.
Problem is that field is not linked with a foreign key (into original table) so I can´t add constraint.
Can anyone explain me how it occurs? or there any way to do constraint without foreign key? Regards
ALTER TABLE Reclutamiento.EvaluacionDetalleCompetenciasFuncionales
ADD IdNivelDominio INT NOT NULL DEFAULT 0;
You're trying to add a new column that should be NOT NULL to table with data. You need to specify what value will be in that new column because it's NOT NULL
Related
I would like to create a new column called PurchaseOrderID in an existing table using SSMS. It combines LineNumber and PONUMBER to create a surrogate key and then I would enter into table design mode and assign it a PK there.
Creating new column:
ALTER TABLE FactPurchaseOrders
ADD PurchaseOrderID VARCHAR(64);
Populating with values:
UPDATE FactPurchaseOrders
SET PurchaseOrderID = (CONVERT(VARCHAR(64), LineNumber) + CONVERT(VARCHAR(64), PONUMBER))
WHERE 1=1;
Currently with this I am unable to assign this column a PK and I believe because it is nullable.
I have also tried creating it in design mode first and the same problem occurs.
That is most certainly the case. After you have run your update, simply alter the columns you will use in your PK to NOT NULL. Since the columns will have values now it can be set as NOT NULL and then it will allow the assignment of PK. Also make sure there isn't already another PK on the table already. There can be only 1!
Update Records
Alter columns to not null
Create PK on fields
Is there any way to simply add not null unique column to existing table. Something like default = 1++ ? Or simply add unique column?
I tried to add column and then put unique contrain but MS SQL says that:
The CREATE UNIQUE INDEX statement terminated because a duplicate key was found for the object name (...) The duplicate key value is ( < NULL > ).
Any way to simply add column to existing working table with unique constrain? Should MS SQL really think that null IS a value?
Add not null column with some default.
Update column to be a sequential integers (see row_number() function)
Add UNIQUE constraint or UNIQUE index over new column
You can add IDENTITY column to a table (but from question it is not clear if you need it or not).
IDENTITY is all you need:
ALTER TABLE TestTable
ADD ID INT IDENTITY(1, 1)
If you want an autonumber, you can add an identity.
If you need to populate the values yourself, you add the column allowing nulls, update the values, check to make sure they are unique and that there are no nulls, then add the unique constraint and trhe not null property. It is best to do this during a maintenance window when no one else would be changing data in that table.
My Problem is to make the Column email NOT NULL AND UNIQUE
ALTER TABLE benutzer ADD email VARCHAR(75) UNIQUE;
works fine but
ALTER TABLE benutzer ADD email VARCHAR(75) UNIQUE NOT NULL;
or
ALTER TABLE benutzer ADD email VARCHAR(75) UNIQUE ,NOT NULL;
work not fine :-(
the error is:
FEHLER: Syntaxerror by „NULL“
I don't understand the Problem from Postgresql >.<
EDIT:
I have solve the Problem.
The Solution for my Problem is to delete the records in my Table.
It is not possible to add a new column that is both UNIQUE and NOT NULL at the same time, when it contains existing records.
The reason for this is due to the fact that adding a column gives it null values to start with, and simultaneously saying there are not allowed to nulls is a contradiction.
The solution is to remove your data, add the column then add the data back
OR
create unique default data for the new column
OR
create the column first, generate unique data for it, then add NOT NULL afterwards
for reference another answer with more info: Create unique constraint with null columns
I'm trying to add a new column to my exiting table but I keep getting an error trying to insert non-null columns.
I understand how this would be an issue to existing databases with lots of data, but my database has no data yet so I'm confused as to why I'm getting this error.
Is there an easy solution for this (I don't want to add default values)
You've got two options, feed it a default value, or add the field without the non-null constraint, then alter the table later to add the non-null constraint after you've populated the field.
This works fine when the table is empty.
CREATE TABLE X(Y INT)
ALTER TABLE T ADD Y INT NOT NULL
There is no need to add a temporary default constraint or create it as NULL, populate then ALTER except if the table is, in fact, not empty as claimed.
I don't think that table is as empty as you think it is.
Try this:
Truncate Table <YourTableName>
Then try the alter table statement.
I have a sybase db table in which i need to add a new column.
The conditions: The column must not allow nulls and be unique.
what is the alter table sql to achieve this?
EDIT:
It is a varchar type column.Yes the table as of now is empty, but when filled it is ensured that unique values would be filled in.
I tired executing
alter table Test add Name varchar not null unique
i get error saying default value must be specified as not null is given.
but i want to add unique constraint so do i really need to specify default?
thanks
Unique values are specified as part of an index on the column, not in the column definition itself.
Try:
alter table Test add Name varchar not null
create unique index index_name_unique on Test (Name)
The ASE reference manual can help with more detail.
Once a table has been created Sybase ASE does not allow addition of NOT NULL column directly unless a default is specified for the column. However, if the table is still empty you can do the following -
First add the new column as a NULL column to the table using alter table command -
alter table Test add Name varchar(100) null
Once this has been done, try modifying the same column Name in the table Test using the alter table script -
alter table Test modify Name varchar(100) NOT NULL
and you will see that you are able to modify the Name column to a NOT NULL column using these steps. This is because at this time Sybase server checks as there is no data in the table hence the NOT NULL constraint is not checked and the column is made NOT NULL. Hence, we are able to skip the default constraint.
In case there would have been some data already present in the table Test, then we need to add one more step in between steps 1 and 2 which will add default values to the existing rows in the table. This can be done via a script for previous data and then following the step 2.
To make the column only allow unique values for the column you need to add a unique key constraint using the following syntax -
alter table Test add constraint UK1 unique(Name)