What I have is several tables...two of them being:
CREATE TABLE Orders(
oid int NOT NULL,
rdate date,
sdate date,
cid int NOT NULL,
eid int NOT NULL,
PRIMARY KEY (oid),
FOREIGN KEY (cid) REFERENCES Customer(cid),
FOREIGN KEY (eid) REFERENCES Employee(eid));
CREATE TABLE PartOrder(
poid int NOT NULL,
pid int NOT NULL,
oid int NOT NULL,
PRIMARY KEY (poid),
FOREIGN KEY (pid) REFERENCES Part(pid),
FOREIGN KEY (oid) REFERENCES Orders(oid));
What I need to do is this:
Create and execute a query that deletes all PartOrder records for Orders for which the shipping date is in the past.
So, I came up with this...
DELETE
FROM (SELECT * FROM PartOrder FULL OUTER JOIN Orders ON partorder.oid=orders.oid)
WHERE sdate<sysdate;
This is giving me this error:
ORA-01752: cannot delete from view without exactly one key-preserved table
Can someone offer me some insight?
I'd write this as something like
DELETE FROM PARTORDER
WHERE POID IN (SELECT p.POID
FROM PARTORDER p
INNER JOIN ORDERS o
ON o.OID = p.OID
WHERE o.SDATE < SYSDATE);
Best of luck.
Related
CREATE TABLE Flight (
FlightNo int NOT NULL PRIMARY KEY,
FlightDate Date,
PlaneSerialNo int,
EmployeeID int,
RouteNo int,
CONSTRAINT FK_PlaneSerialNo FOREIGN KEY(PlaneSerialNo)
REFERENCES Plane(PlaneSerialNo),
CONSTRAINT FK_EmployeeID FOREIGN KEY(EmployeeID)
REFERENCES Employee(EmployeeID),
CONSTRAINT FK_RouteNo FOREIGN KEY(RouteNo)
REFERENCES Route(RouteNo)
);
trying to create a sort of database system using oracle where it tracks flights but it just says the name is already used but havent seen any similarities in constraints other than identifying FKs
Oracle doesn't rely much on similarities - it has found object with exactly the same name in its dictionary and - as you can't have two objects with the same name - it raised the error.
Query user_constraints (and then user_objects, if previous search didn't find anything).
If you want to find out which table it is, you might try
select owner, table_name from dba_constraints where constraint_name = '<some value from your create table command>';
I have 4 tables
customer: CustomerID - primary key, name
Magazine: name - primary key, cost, noofissues
Newspaper: name - primary key, cost, noofissues
subscription: custID - references CustomerID of Customer, name, startdate, enddate
In the above, can I reference the name from subscription table to reference name from Magazine and name from Newspaper?
I have created the tables Customer, Newspaper and Magazine. I only need to create Subscription.
Can you do something like this?
CREATE TABLE subscription (
custID INT
CONSTRAINT subscription__custid__fk REFERENCES Customer( CustomerId ),
name VARCHAR2(50)
CONSTRAINT subscription__mag_name__fk REFERENCES Magazine( Name )
CONSTRAINT subscription__news_name__fk REFERENCES Newspaper( Name ),
startdate DATE
CONSTRAINT subscription__startdate__nn NOT NULL,
enddate DATE
);
Yes, you can and you will have two foreign keys on the same column pointing to different tables but if the value in the column is non-null then it will expect there to be a matching name in both the magazines table and the newspapers table - which is probably not what you are after.
Can you have a foreign key that asks can the value be in either exclusively in this table or that table (but not in both)? No.
But you can re-factor your database so you merge the newspapers and magazines tables into a single table (which you can then easily reference); like this:
CREATE TABLE customer (
CustomerID INT
CONSTRAINT customer__CustomerId__pk PRIMARY KEY,
name VARCHAR2(50)
CONSTRAINT customer__name__nn NOT NULL
);
CREATE TABLE Publications (
id INT
CONSTRAINT publications__id__pk PRIMARY KEY,
name VARCHAR2(50)
CONSTRAINT publications__name__nn NOT NULL,
cost NUMBER(6,2)
CONSTRAINT publications__cost__chk CHECK ( cost >= 0 ),
noofissues INT,
type CHAR(1),
CONSTRAINT publications__type__chk CHECK ( type IN ( 'M', 'N' ) )
);
CREATE TABLE subscription (
custID INT
CONSTRAINT subscription__custid__fk REFERENCES Customer( CustomerId ),
pubID INT
CONSTRAINT subscription__pubid__fk REFERENCES Publications( Id ),
startdate DATE
CONSTRAINT subscription__startdate__nn NOT NULL,
enddate DATE
);
If you are asking whether you can create a foreign key constraint on subscription that references either the newspaper table or the magazine table, the answer is no, you cannot. A foreign key must reference exactly one primary key.
Since magazine and newspaper have the same set of attributes, the simple option is to combine them into a single periodical table with an additional periodical_type column to indicate whether it is a magazine or a newspaper. You could then create your foreign key to the periodical table.
Although it probably won't make sense in this particular example, you could also have separate columns in subscription for magazine_name and newspaper_name and create separate foreign key constraints on those columns along with a check constraint that ensured that exactly one of the values was non-NULL. That might make sense if the two different parent tables had radically different attributes.
Not related to your question but as a general bit of advice, I wouldn't use the name as the primary key. In addition to being rather long, names tend to change over time and names aren't necessarily unique. I would use a different attribute for the key, potentially a synthetic primary key generated from a sequence.
I have two tables
Parent table
(account_number varchar(15) not null,
branch_name varchar(50) not null,
balance number not null,
primary key(account_number));
Child table
account_number varchar(15) not null,
foreign key(account_number) references parent table(account_number));
I am trying this:
DELETE FROM parent table
WHERE balances > 1000;
I am deleting accounts by balances on the parent but I get an error message about the child relationship.
My assumption is a DELETE CASCADE has to be added to the foreign key in the child table. All the documentation shows how to alter the table when the constraint is named. I do not have that situation. Is there a way to do it, or do I have to specify the cascade in the delete statement I am writing?
Every constraint in Oracle has a name. If a name isn't specified when the constraint is created, Oracle will autogenerate a name for the constraint. If you don't know what the name of a constraint is, try running a SQL statement that violates the constraint and reading the constraint name from the error message:
SQL> delete from parent where account_number = 1234;
delete from parent where account_number = 1234
*
ERROR at line 1:
ORA-02292: integrity constraint (LUKE.SYS_C007357) violated - child record
found
In this case the name of the constraint is SYS_C007357.
If that doesn't work, you can query the data dictionary view user_constraints:
SQL> select constraint_name from user_constraints where table_name = 'CHILD' and constraint_type = 'R';
CONSTRAINT_NAME
------------------------------
SYS_C007357
As far as I can tell, you can't modify a foreign key constraint to enable ON DELETE CASCADE. Instead you must drop the constraint and recreate it.
I don't believe you can apply the CASCADE option to a DELETE statement either, but you can delete the child rows before deleting from the parent:
DELETE FROM child
WHERE account_number IN (SELECT account_number FROM parent WHERE balance > 1000);
DELETE FROM parent
WHERE balance > 1000;
However, I don't know how many other tables you have with foreign key constraints referencing your parent table, nor in how many places you are deleting from the parent table, so I can't say how much work it would be to use this approach.
yes you can set DELETE CASCADE
see more info here FOREIGN KEYS WITH CASCADE DELETE
CREATE TABLE table_name
(
column1 datatype null/not null,
column2 datatype null/not null,
...
CONSTRAINT fk_column
FOREIGN KEY (column1, column2, ... column_n)
REFERENCES parent_table (column1, column2, ... column_n)
ON DELETE CASCADE
);
for example
CREATE TABLE supplier
( supplier_id numeric(10) not null,
supplier_name varchar2(50) not null,
contact_name varchar2(50),
CONSTRAINT supplier_pk PRIMARY KEY (supplier_id)
);
CREATE TABLE products
( product_id numeric(10) not null,
supplier_id numeric(10) not null,
CONSTRAINT fk_supplier
FOREIGN KEY (supplier_id)
REFERENCES supplier(supplier_id)
ON DELETE CASCADE
);
I've used the CREATE VIEW command to create a view (obviously), and join multiple tables. The CREATE VIEW command works perfectly, but when I try to update the VIEW RentalInfoOct, I receive error "ORA-01779: cannot modify a column which maps to a non key-preserved table"
CREATE VIEW RentalInfoOct
(branch_no, branch_name, customer_no, customer_name, item_no, rental_date)
AS
SELECT i.branchNo, b.branchName, r.customerNo, c.customerName, i.itemNo, r.dateFrom
FROM item i
INNER JOIN rental r
ON i.itemNo = r.itemNo
INNER JOIN branch b
ON i.branchNo = b.branchNo
INNER JOIN customer c
ON r.customerNo = c.customerNo
WHERE r.dateFrom
BETWEEN to_date('10-01-2009','MM-DD-YYYY')
AND to_date('10-31-2009','MM-DD-YYYY')
My update command.
UPDATE RentalInfoOct
SET item_no = '3'
WHERE customer_name = 'April Alister'
AND branch_name = 'Kingsway'
AND rental_date = '10/28/2009'
I'm not sure if this will help in solving the problem, but here are my CREATE TABLE commands
CREATE TABLE Branch
(
branchNo SMALLINT NOT NULL,
branchName VARCHAR(20) NOT NULL,
branchAddress VARCHAR(40) NOT NULL,
PRIMARY KEY (BranchNo)
);
--Item Table Definition
CREATE TABLE Item
(
branchNo SMALLINT NOT NULL,
itemNo SMALLINT NOT NULL,
itemSize VARCHAR(8) NOT NULL,
price DECIMAL(6,2) NOT NULL,
PRIMARY KEY (ItemNo, BranchNo),
FOREIGN KEY (BranchNo) REFERENCES Branch ON DELETE CASCADE,
CONSTRAINT VALIDAMT
CHECK (price > 0)
);
-- Customer Table Definition
CREATE TABLE Customer
(
customerNo SMALLINT NOT NULL,
customerName VARCHAR(15) NOT NULL,
customerAddress VARCHAR(40) NOT NULL,
customerTel VARCHAR(10),
PRIMARY KEY (CustomerNo)
);
-- Rental Table Definition
CREATE TABLE Rental
(
branchNo SMALLINT NOT NULL,
customerNo SMALLINT NOT NULL,
dateFrom DATE NOT NULL,
dateTo DATE,
itemNo SMALLINT NOT NULL,
PRIMARY KEY (BranchNo, CustomerNo, dateFrom),
FOREIGN KEY (BranchNo) REFERENCES Branch(BranchNo) ON DELETE CASCADE,
FOREIGN KEY (CustomerNo) REFERENCES Customer(CustomerNo) ON DELETE CASCADE,
CONSTRAINT CORRECTDATES CHECK (dateTo > dateFrom OR dateTo IS NULL)
);
See: Oracle: multiple table updates => ORA-01779: cannot modify a column which maps to a non key-preserved table
You're attempting to update a view with joins, but the join conditions are not based on a uniqueness constraint, which creates the possibility of multiple rows that are created from a single row in one table.
It seems like you need a Unique Key - Foreign Key relationship between the columns your join condition is based on.
EDIT: I just saw your edit. Changing r.branchNo = b.branchNo to i.branchNo = b.branchNo should go a long way. Not sure how well r.customerNo = c.customerNo will work out.
A simple stored procedure that I want to handle with LINQ instead:
SELECT
CASE WHEN mg.MovieID IS NULL THEN 0 else 1 end as Selected ,
g.genreID, g.GenreName
FROM dbo.Genres g LEFT JOIN
(
SELECT MovieID, GenreID FROM [dbo].[MovieGenre] m
WHERE m.MovieID = #Movie
) MG
ON g.[GenreID] = mg.[GenreID]
ORDER BY g.GenreName
I think this should be simple and I think it would be a common requirement, yet I can't figure it out nor have I found a solution via searching the web.
The app is in WPF backed by an EF model. Since EF hides the join table I need LINQ syntax that can deal with the absence of the intermediary table.
Classic many-to-many with a simple join table: table 1:Movies, table 2: Genres, Join table: MovieGenres. In the UI the user selects a specfic movie. For that movie I want to bring back ALL the genres and a bool value indicating whether the genre has been assigned to the movie. Hours of attempting this in LINQ have failed me, so the solution is currently to have the stored procedure above generate the values for me. I won't always be abe to do this with a stored procedure and would love to see a LINQ solution.
Here's the actual SQL table structures
CREATE TABLE [dbo].[Genres](
[GenreID] [int] IDENTITY(1,1) NOT NULL,
[GenreName] [nvarchar](15) NOT NULL,
CONSTRAINT [PK_Genres] PRIMARY KEY CLUSTERED
(
[GenreID] ASC
)) ON [PRIMARY]
GO
CREATE TABLE [dbo].[Movies](
[MovieID] [int] IDENTITY(1,1) NOT NULL,
[MovieTitle] [nvarchar](50) NOT NULL,
CONSTRAINT [PK_Movies] PRIMARY KEY CLUSTERED
(
[MovieID] ASC
))
ON [PRIMARY]
GO
CREATE TABLE [dbo].[MovieGenre](
[MovieID] [int] NOT NULL,
[GenreID] [int] NOT NULL,
CONSTRAINT [PK_MovieGenre] PRIMARY KEY CLUSTERED
(
[MovieID] ASC,
[GenreID] ASC
)) ON [PRIMARY]
GO
ALTER TABLE [dbo].[MovieGenre] WITH CHECK ADD CONSTRAINT [FK_Genres] FOREIGN KEY([GenreID])
REFERENCES [dbo].[Genres] ([GenreID])
GO
ALTER TABLE [dbo].[MovieGenre] CHECK CONSTRAINT [FK_Genres]
GO
ALTER TABLE [dbo].[MovieGenre] WITH CHECK ADD CONSTRAINT [FK_Movies] FOREIGN KEY([MovieID])
REFERENCES [dbo].[Movies] ([MovieID])
GO
ALTER TABLE [dbo].[MovieGenre] CHECK CONSTRAINT [FK_Movies]
GO
This should do the trick.
use from and in with the navigation property for a join
DefaultIfEmpty to make it a left join
Using a ternary operator ? : for the case statement
Query:
var query = from g in context.Genres
from m in g.Movies.Where(x => x.MovieID == movieId)
.DefaultIfEmpty()
orderby g.GenreName
select new {
Selected = m == null ? 0 : 1,
g.genreID,
g.GenreName
};