These are the tables I already have:
CREATE TABLE Gyartok
(
GyID INT IDENTITY(2, 3),
Nev VARCHAR(20),
CONSTRAINT PK_Gyartok PRIMARY KEY (GyID)
)
CREATE TABLE Focicsuka
(
CsID INT IDENTITY(2, 2),
Meret INT,
CONSTRAINT PK_Focicsuka PRIMARY KEY (CsID)
)
CREATE TABLE FcsGyartjaGya
(
GyID INT IDENTITY(3, 2),
CsID INT,
Ar INT,
CONSTRAINT FK_FcsGyartjaGya1
FOREIGN KEY (GyID) REFERENCES Gyartok(GyID),
CONSTRAINT FK_FcsGyartjaGya2
FOREIGN KEY (CsID) REFERENCES Focicsuka(CsID),
CONSTRAINT PK_FcsGyartjaGya
PRIMARY KEY (GyID, CsID)
)
The problem is that every time I try to add new values to the table (like such)
INSERT INTO FcsGyartjaGya (Ar) VALUES (300);
I get an error saying I didn't initialize the CsID INT column:
Cannot insert the value NULL into column 'CsID', table 'Lab3.dbo.FcsGyartjaGya'; column does not allow nulls. INSERT fails.
I know I must initialize it with something, but I have no idea what do to it with, because IDENTITY(x, y) doesn't work (it's occupied by another column already) and adding another parameter to the code (like such)
INSERT INTO FcsGyartjaGya (Ar, CsID) VALUES (300, 7);
creates another error which says
The INSERT statement conflicted with the FOREIGN KEY constraint "FK_FcsGyartjaGya1". The conflict occurred in database "Lab3a", table "dbo.Gyartok", column 'GyID'.
It is important to note that I already filled every column with data, so that couldn't be the problem.
As I mention in the comments, your INSERT will work fine, provided the stars align correctly. For your table Gyartok you have GyID as your PRIMARY KEY, which is defined as a IDENTITY(2,3); so the first value generated is 2 and then each row attempted to be INSERTed will increment by 3.
So, if we run the following, we get the IDs 2, 5, 7 and 17. (11 and 14 are skipped as the INSERT failed).
CREATE TABLE Gyartok (
GyID INT IDENTITY(2, 3),
Nev VARCHAR(20),
CONSTRAINT PK_Gyartok PRIMARY KEY (GyID)
);
GO
INSERT INTO dbo.Gyartok (Nev)
VALUES ('asdfjahsbvd'),
('ashjkgdfakd'),
('kldfbhjo');
GO
INSERT INTO dbo.Gyartok (Nev)
VALUES (REPLICATE('A',25)), --Force a truncation error
('ashjkgdfakd');
GO
INSERT INTO dbo.Gyartok (Nev)
VALUES (REPLICATE('A',15));
Let's now add some data for your other table:
CREATE TABLE Focicsuka (
CsID INT IDENTITY(2, 2),
Meret INT,
CONSTRAINT PK_Focicsuka PRIMARY KEY (CsID)
)
INSERT INTO dbo.Focicsuka (Meret)
VALUES(12),
(25);
Now we want to INSERT into the table FcsGyartjaGya, defined as the following:
CREATE TABLE FcsGyartjaGya (
GyID INT IDENTITY(3, 2),
CsID INT,
Ar INT,
CONSTRAINT FK_FcsGyartjaGya1 FOREIGN KEY (GyID) REFERENCES Gyartok(GyID),
CONSTRAINT FK_FcsGyartjaGya2 FOREIGN KEY (CsID) REFERENCES Focicsuka(CsID),
CONSTRAINT PK_FcsGyartjaGya PRIMARY KEY (GyID, CsID)
)
This has a IDENTITY on GyID, but defined as an IDENTITY(3,2), so the first value is 3 and then incremented by 2.
As this has 2 foreign keys, on GyID and CsID when we INSERT the row the values must appear in the respective tables. As GyID is defined as anIDENTITY(3,2) however, this is where we need to rely on the Stars luck for the INSERT to work. Why? Well 2 + (3*n) and 3+(2*n) can give very different numbers. The first are as you saw at the start of this answer. For the latter, we have numbers like 3, 5, 7, 9, 11. As you can see, only 1 in 3 of these numbers match a number in our original sequence, so luck is what we are going to be relying on.
Let's, therefore, try a single INSERT.
INSERT INTO dbo.FcsGyartjaGya (CsID,Ar)
VALUES(2,1);
The INSERT statement conflicted with the FOREIGN KEY constraint "FK_FcsGyartjaGya1". The conflict occurred in database "Sandbox", table "dbo.Gyartok", column 'GyID'.
Well, that didn't work, but it was expected. 3 isn't a value in the table Gyartok. Let's try again!
INSERT INTO dbo.FcsGyartjaGya (CsID,Ar)
VALUES(2,2);
It worked! The stars Luck was our side, and the IDENTITY value was a value in the table Gyartok. Let's try a couple of rows this time!
INSERT INTO dbo.FcsGyartjaGya (CsID,Ar)
VALUES(4,3),
(4,4);
The INSERT statement conflicted with the FOREIGN KEY constraint "FK_FcsGyartjaGya1". The conflict occurred in database "Sandbox", table "dbo.Gyartok", column 'GyID'.
No!! Not again. :( That's because the stars didn't align; 7 and 9 aren't in the other table. But wait, 11 was in the sequence, so let's try that:
INSERT INTO dbo.FcsGyartjaGya (CsID,Ar)
VALUES(4,5);
Error, again?! No, it cannot be!!! :( Oh wait, I forgot, the stars were against us before, because that INSERT failed against Gyartok for the value of 11. I need to wait for 17!
--13 fails
INSERT INTO dbo.FcsGyartjaGya (CsID,Ar)
VALUES(4,6);
GO
--15 fails
INSERT INTO dbo.FcsGyartjaGya (CsID,Ar)
VALUES(4,6);
GO
--17 works!
INSERT INTO dbo.FcsGyartjaGya (CsID,Ar)
VALUES(4,6);
And now we have another row in our table.
So what is the problem? Your design. GyID is defined as an IDENTITY and a FOREIGN KEY; meaning you are at the "whims" of SQL Server generating a value valid. This is not what you want. Just don't define the column as an IDENTITY and then INSERT the data with all 3 of your columns defined:
CREATE TABLE FcsGyartjaGya (
GyID int,-- IDENTITY(3, 2),
CsID INT,
Ar INT,
CONSTRAINT FK_FcsGyartjaGya1 FOREIGN KEY (GyID) REFERENCES Gyartok(GyID),
CONSTRAINT FK_FcsGyartjaGya2 FOREIGN KEY (CsID) REFERENCES Focicsuka(CsID),
CONSTRAINT PK_FcsGyartjaGya PRIMARY KEY (GyID, CsID)
)
GO
INSERT INTO dbo.FcsGyartjaGya (GyID, CsID, Ar)
VALUES(2,2,1),
(2,4,2),
(5,4,3),
(8,2,4),
(8,4,5);
And all these rows insert fine.
I think there is a bit confusion, if I understand correctly what You're trying to do, then you have two tables each with their own id, which is based on an identity column, so you get new values in those for free.
Then you are trying to make a relation table with extra data.
Issue 1: You cannot have FcsGyartjaGya.GyID be identity if it refers to Gyartok.GyID because you will want to insert into it and not rely on an auto increment. If it doesn't refer to the same it should have another name or my head will possibly explode :))
Issue 2: When populating a relation table you need to insert it with what pairs you want, there is no way SQL server can know how it should match these identity pairs in the relation table
I think this is what people are aiming at in the comments, for example
to insert a relationship between row with Focicsuka.CsID = 1 to Gyartok.GyID 7 and adding Ar = 300 have to look like
INSERT INTO FCSGYARTJAGYA(GYID, CSID, AR)
VALUES(7, 1, 300)
Unless You've forgotten to mention that you want to put some value for each of some value or based on something which can be scripted, in other words unless You have logics to define the pairs and their values, relationship tables cannot have defaults on their foreign key fields.
I have a table that I create independently, the primary key is set with the serial type and a sequence applied to the table, but when I try to insert a value a NULL CONSTRAINT error is thrown and the return looks like null was passed, am I missing something in the INSERT statement?
SQL for table generation:
DROP TABLE IF EXISTS public."Team" CASCADE;
CREATE TABLE public."Team" (
"IdTeam" serial PRIMARY KEY,
name text NOT null,
CONSTRAINT "pKeyTeamUnique" UNIQUE ("IdTeam")
);
ALTER TABLE public."Team" OWNER TO postgres;
DROP SEQUENCE IF EXISTS public."Team_IdTeam_seq" CASCADE;
CREATE SEQUENCE public."Team_IdTeam_seq"
AS integer
START WITH 1
INCREMENT BY 1
NO MINVALUE
NO MAXVALUE
CACHE 1;
ALTER TABLE public."Team_IdTeam_seq" OWNER TO postgres;
ALTER SEQUENCE public."Team_IdTeam_seq" OWNED BY public."Team"."IdTeam";
SQL for insert :
INSERT INTO public."Team" (name) values ('Manchester Untited');
The returning error:
ERROR: null value in column "IdTeam" violates not-null constraint
DETAIL: Failing row contains (null, Manchester Untited).
SQL state: 23502
I am baffled. Why are you trying to define your own sequence when the column is already defined as serial?
Second, a primary key constraint is already unique. There is no need for a separate unique constraint.
Third, quoting identifiers just makes the code harder to write and to read.
You can just do:
DROP TABLE IF EXISTS public.Team CASCADE;
CREATE TABLE public.Team (
IdTeam serial PRIMARY KEY,
name text NOT null
);
INSERT INTO public.Team (name)
VALUES ('Manchester Untited');
Dropping the sequence causes the default definition for the IdTeam column to be dropped. After recreating the sequence you will have to recreate the default definition.
I'd like to add a NOT NULL column to a Redshift table that has records, an IDENTITY field, and that other tables have foreign keys to.
In PostgreSQL, you can add the column as NULL, fill it in, then ALTER it to be NOT NULL.
In Redshift, the best I've found so far is:
ALTER TABLE my_table ADD COLUMN new_column INTEGER;
-- Fill that column
CREATE TABLE my_table2 (
id INTEGER IDENTITY NOT NULL SORTKEY,
(... all the fields ... )
new_column INTEGER NOT NULL,
PRIMARY KEY(id)
) DISTSTYLE all;
UNLOAD ('select * from my_table')
to 's3://blah' credentials '<aws-auth-args>' ;
COPY my_table2
from 's3://blah' credentials '<aws-auth-args>'
EXPLICIT_IDS;
DROP table my_table;
ALTER TABLE my_table2 RENAME TO my_table;
-- For each table that had a foreign key to my_table:
ALTER TABLE another_table ADD FOREIGN KEY(my_table_id) REFERENCES my_table(id)
Is this the best way of achieving this?
You can achieve this w/o having to load to S3.
modify the existing table to create the desired column w/ a default value
update that column in some way (in my case it was copying from another column)
create a new table with the column w/o a default value
insert into the new table (you must list out the columns rather than using (*) since the order may be the same (say if you want the new column in position 2)
drop the old table
rename the table
alter table to give correct owner (if appropriate)
ex:
-- first add the column w/ a default value
alter table my_table_xyz
add visit_id bigint NOT NULL default 0; -- not null but default value
-- now populate the new column with whatever is appropriate (the key in my case)
update my_table_xyz
set visit_id = key;
-- now create the new table with the proper constraints
create table my_table_xzy_new
(
key bigint not null,
visit_id bigint NOT NULL, -- here it is not null and no default value
adt_id bigint not null
);
-- select all from old into new
insert into my_table_xyz_new
select key, visit_id, adt_id
from my_table_xyz;
-- remove the orig table
DROP table my_table_xzy_events;
-- rename the newly created table to the desired table
alter table my_table_xyz_new rename to my_table_xyz;
-- adjust any views, foreign keys or permissions as required
we want to create a trigger which checks if a new measurement (=messung) point lies within the current glacier shape (=umriss).
are tables look like this:
glacier shape (=Umriss)
create table umriss
(
umr_nr number (4) not null,
umr_datum date,
GLST_ID number (4) not null,
shape mdsys.sdo_geometry,
GLETSCHER_ID number (3) not null
)
;
alter table umriss
add constraint umriss_glst_pk
primary key (umr_nr, GLST_ID, GLETSCHER_ID)
;
ALTER TABLE umriss
ADD CONSTRAINT umriss_gletscherstand_fk
FOREIGN KEY (GLST_ID, GLETSCHER_ID)
REFERENCES GLETSCHERSTAND(GLST_ID, GLETSCHER_ID);
new measurement (=Messung)
CREATE TABLE MESSUNG
(
MESS_NR number (4) not null,
MESS_DAT date,
MESS_AKK number (20) NOT NULL,
MESS_SCHMELZ number (20) NOT NULL,
SHAPE mdsys.sdo_geometry,
MESS_BILD blob,
KMPGN_NR NUMBER (4) NOT NULL
);
ALTER TABLE MESSUNG
ADD CONSTRAINT messung_pk
PRIMARY KEY (MESS_NR);
ALTER TABLE MESSUNG
ADD CONSTRAINT messung_messkampagne_fk
FOREIGN KEY (KMPGN_NR)
REFERENCES MESSKAMPAGNE(KMPGN_NR);
Trigger
CREATE OR REPLACE
TRIGGER MESSUNG_in_UMRISS_TRI
BEFORE INSERT OR UPDATE ON MESSUNG
FOR EACH ROW
DECLARE
num_check NUMBER;
BEGIN
SELECT COUNT (*) INTO num_check
FROM UMRISS u
WHERE mdsys.sdo_contains (u.shape, :NEW.point) = 'TRUE';
IF num_check <> 1
THEN
RAISE_APPLICATION_ERROR (=20500, 'Messung in keinem Umriss')
END IF;
END;
How do we iplement the function so the trigger only checks within the most curretn glacier shape?
Thanks for your help!
This will return the one row fron UMRISS which matches the most recent date in the table.
SELECT COUNT (*) INTO num_check
FROM UMRISS u
WHERE mdsys.sdo_contains (u.shape, :NEW.point) = 'TRUE'
AND u.umr_datum = ( select max(d.;umr_datum) from UMRISS d );
This sort of query is the price for keeping historical data in teh same table as the current record.
it seems that POINT ist not defined in your example?
However, you might consider a check constraint because a trigger would only be enforced when a MESSUNG record is inserted or updated, but not when UMRISS is changed
alter table MESSUNG add constraint MESSUNG_CC_CONTAINS check(mdsys.sdo_contains (shape, point) = 'TRUE')
In case you're frequently updating the UMRISS records it might not be feasable at all to enforce such a constraint because Oracle would have to check all MESSUNG records when UMRISS is updated or deleted. Perhaps consider an additional mapping table between MESSUNG and UMRISS that you can update separately.
I have a foreign key constraint between tables Sessions and Users. Specifically, Sessions.UID = Users.ID. Sometimes, I want Sessions.UID to be null. Can this be allowed? Any time I try to do this, I get an FK Constraint Violation.
Specifically, I'm inserting a row into Sessions via LINQ. I set the Session.User = null; and I get this error:
An attempt was made to remove a relationship between a User and a Session. However, one of the relationship's foreign keys (Session.UID) cannot be set to null.
However, when I remove the line that nulls the User property, I get this error on my SubmitChanges line:
Value cannot be null.
Parameter name: cons
None of my tables have a field called 'cons', nor is it in my 5,500-line DataContext.designer.cs file, nor is it in the QuickWatch for any of the related objects, so I have no idea what 'cons' is.
In the Database, Session.UID is a nullable int field and User.ID is a non-nullable int. I want to record sessions that may or may not have a UID, and I'd rather do it without disabling constraint on that FK relationship. Is there a way to do this?
I seemed to remember creating a nullable FK before, so I whipped up a quick test. As you can see below, it is definitely doable (tested on MSSQL 2005).
Script the relevant parts of your tables and constraints and post them so we can troubleshoot further.
CREATE DATABASE [NullableFKTest]
GO
USE [NullableFKTest]
GO
CREATE TABLE OneTable
(
OneId [int] NOT NULL,
CONSTRAINT [PK_OneTable] PRIMARY KEY CLUSTERED
(
[OneId] ASC
)
)
CREATE TABLE ManyTable (ManyId [int] IDENTITY(1,1) NOT NULL, OneId [int] NULL)
GO
IF NOT EXISTS (SELECT * FROM sys.foreign_keys WHERE object_id = OBJECT_ID(N'[dbo].[FK_ManyTable_OneTable]') AND parent_object_id = OBJECT_ID(N'[dbo].[ManyTable]') )
ALTER TABLE [dbo].[ManyTable] WITH CHECK ADD CONSTRAINT [FK_ManyTable_OneTable] FOREIGN KEY([OneId])
REFERENCES [dbo].[OneTable] ([OneId])
GO
--let's get a value in here
insert into OneTable(OneId) values(1)
select* from OneTable
--let's try creating a valid relationship to the FK table OneTable
insert into ManyTable(OneId) values (1) --fine
--now, let's try NULL
insert into ManyTable(OneId) values (NULL) --also fine
--how about a non-existent OneTable entry?
insert into ManyTable(OneId) values (5) --BOOM! - FK violation
select* from ManyTable
--1, 1
--2, NULL
--cleanup
ALTER TABLE ManyTable DROP CONSTRAINT FK_ManyTable_OneTable
GO
drop TABLE OneTable
GO
drop TABLE ManyTable
GO
USE [Master]
GO
DROP DATABASE NullableFKTest