In my job, checking the database diagrams I have found a One-to-one relation between two tables, but the relation is not between two primary keys, the relation is between a primary key in one table and other non primary key attribute in the other table. In the database diagrams appear as "One to One relation". I wonder how can I create this kind of relationship "One to One" using just one primary on one table and using a non primary key in the other table.
Here are the scripts for "create" that I found in the database
---------------To create table Agreement Documents--------------
CREATE TABLE [dbo].[AgreementDocuments](
[AgreementDocumentID] [int] IDENTITY(1,1) NOT NULL,
[AgreementID] [int] NOT NULL,
[Document] [varbinary](max) NOT NULL,
CONSTRAINT [PK_AgreementDocuments] PRIMARY KEY CLUSTERED
([AgreementDocumentID] ASC) WITH (PAD_INDEX = OFF,
STATISTICS_NORECOMPUTE = OFF,
IGNORE_DUP_KEY = OFF,
ALLOW_ROW_LOCKS = ON,
ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
ALTER TABLE [dbo].[AgreementDocuments] WITH CHECK ADD CONSTRAINT
[FK_AgreementDocuments_Agreements] FOREIGN KEY([AgreementID])
REFERENCES [dbo].[Agreements] ([AgreementID])
GO
ALTER TABLE [dbo].[AgreementDocuments] CHECK CONSTRAINT
[FK_AgreementDocuments_Agreements]
GO
--------------------------To create table Agreements-----------------------
CREATE TABLE [dbo].[Agreements](
[AgreementID] [int] IDENTITY(1,1) NOT NULL,
[ContactID] [int] NOT NULL,
[ClientID] [int] NOT NULL,
CONSTRAINT [PK_Agreements] PRIMARY KEY CLUSTERED
([AgreementID] ASC) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE =
OFF, IGNORE_DUP_KEY = OFF,
ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]GO
If I run this two queries in a separate database, it creates two tables with "One to Many" relation. How is that possible?
You can make this a one-to-one relationship by adding a UNIQUE CONSTRAINT to the AgreementID field:
ALTER TABLE dbo.AgreementDocuments
ADD CONSTRAINT uq_AgreementDocuments_AgreementId UNIQUE (AgreementId)
With the unique constraint, it will force it to be a one-to-one, rather than a one-to-many:
Before Constraint:
After Constraint:
Create table one with an identifying ID column.
AgreementDocumentID is identity and distinct
In the other table do a foreign key to the first table AgreementDocumentID field. And then put a distinct index on the second table for AgreementDocumentID.
If I understand your question.
No Er-Digram tool works 100% you have to edit what they create to make it right. Depending on the tool quality your amount of edits change.
Related
I have three tables: offices, suboffices, and sales. Each office owns several suboffices, both offices and suboffices sell products. How should I design my sales table to store there office or suboffice where this sale was made?
I was thinking about having a compound foreign key made of office_id and suboffice_id (where suboffice_id may be null, in which case a sale was made in office)
Is it the right way to design a database?
I was also thinking about having two sales tables: for offices and suboffices. But in my opinion it makes things a bit harder..
UPDATE
Sales can be of different types, so they will need different tables. And there will be one table 'SALES' which will store type of a sale and where it was made
Your sub-offices sound the same as your offices from a properties point of view. Here is a diagram of what your table design could look like by having your Office table include a ParentOffice foreign key.
And here is the SQL to create those tables:
CREATE TABLE [dbo].[Office](
[OfficeId] [int] NOT NULL,
[ParentOfficeId] [int] NULL,
[MoreStuff] [nvarchar](50) NULL,
CONSTRAINT [PK_Office] PRIMARY KEY CLUSTERED
(
[OfficeId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[Office] WITH CHECK ADD CONSTRAINT [FK_Office_Office] FOREIGN KEY([ParentOfficeId])
REFERENCES [dbo].[Office] ([OfficeId])
GO
ALTER TABLE [dbo].[Office] CHECK CONSTRAINT [FK_Office_Office]
GO
CREATE TABLE [dbo].[Product](
[ProductId] [int] NOT NULL,
[MoreStuff] [nvarchar](50) NULL,
CONSTRAINT [PK_Product] PRIMARY KEY CLUSTERED
(
[ProductId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
CREATE TABLE [dbo].[Sale](
[SaleId] [int] NOT NULL,
[ProducitId] [int] NOT NULL,
[OfficeId] [int] NOT NULL,
CONSTRAINT [PK_Sale] PRIMARY KEY CLUSTERED
(
[SaleId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[Sale] WITH CHECK ADD CONSTRAINT [FK_Sale_Office] FOREIGN KEY([OfficeId])
REFERENCES [dbo].[Office] ([OfficeId])
GO
ALTER TABLE [dbo].[Sale] CHECK CONSTRAINT [FK_Sale_Office]
GO
ALTER TABLE [dbo].[Sale] WITH CHECK ADD CONSTRAINT [FK_Sale_Sale] FOREIGN KEY([ProducitId])
REFERENCES [dbo].[Product] ([ProductId])
GO
ALTER TABLE [dbo].[Sale] CHECK CONSTRAINT [FK_Sale_Sale]
GO
One way to go about this, assuming OFFICE and SUBOFFICE share many of the same attributes is to eliminate the SUBOFFICE table and add a PARENT_OFFICE_ID column to the OFFICE table. Under this design, the distinction between an office and a sub-office would be whether or not PARENT_OFFICE_ID is null. Then SALES can simply have an OFFICE_ID column that can reference either kind of office.
I want to delete rows on a child table. I receive the error
The DELETE statement conflicted with the REFERENCE constraint
"FK_Address_UserDataSet". The conflict occurred in
database "XYZ", table "dbo.Address", column
'DataSetId'. The statement has been terminated.
I have a database structure with a parent UserDataSet and child Address table (where a parent can have any number of childs).
There is a foreign key constraint (mentioned in the error) that requires the child's DataSetId to relate to a valid UserDataSet.
Here are the table and constraint scripts, created with MS SQL Server Management Studio 2008 in simplified form:
CREATE TABLE [dbo].[Address](
[AddressId] [int] IDENTITY(1,1) NOT NULL,
[DataSetId] [int] NOT NULL,
--other fields
CONSTRAINT [PK_Address] PRIMARY KEY CLUSTERED
(
[AddressId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
---
CREATE TABLE [dbo].[UserDataSet](
[DataSetId] [int] IDENTITY(1,1) NOT NULL,
--other fields
CONSTRAINT [PK_UserDataSet] PRIMARY KEY CLUSTERED
(
[DataSetId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
---Create the constraint
ALTER TABLE [dbo].[Address] WITH NOCHECK ADD CONSTRAINT [FK_Address_UserDataSet] FOREIGN KEY([DataSetId])
REFERENCES [dbo].[UserDataSet] ([DataSetId])
GO
ALTER TABLE [dbo].[Address] CHECK CONSTRAINT [FK_Address_UserDataSet]
GO
But, how can deleting a child (not the parent) be a problem in this setup?
Can it be that the row to delete is currently invalid, probably added while the constraint was not (yet) in use), an the constraint now is enforced while deleting the child with an invalid foreign key?
Why are you adding the constraint with NOCHECK?
From MSDN documentation...
If you do not want to verify new CHECK or FOREIGN KEY constraints
against existing data, use WITH NOCHECK. We do not recommend doing
this, except in rare cases. The new constraint will be evaluated in
all later data updates. Any constraint violations that are suppressed
by WITH NOCHECK when the constraint is added may cause future updates
to fail if they update rows with data that does not comply with the
constraint.
I want to select two columns in my table and make them unique but I don't know how to do it in SQL Azure database. As you can see in the image below, it doesn't show any option to modify the table properties, so everything is done using sql queries:
Here is the generated script of the table:
USE [mydbase]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[clientaccess](
[ID] [bigint] IDENTITY(1,1) NOT NULL,
[ModuleName] [nvarchar](50) NOT NULL,
[ClientAuthenticationId] [bigint] NOT NULL,
[HasAccess] [bit] NOT NULL,
CONSTRAINT [PK_clientaccess_ID] PRIMARY KEY CLUSTERED
(
[ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON)
)
GO
ALTER TABLE [dbo].[clientaccess] WITH CHECK ADD CONSTRAINT [CAI_caID] FOREIGN KEY([ClientAuthenticationId])
REFERENCES [dbo].[clientauthentication] ([ID])
GO
ALTER TABLE [dbo].[clientaccess] CHECK CONSTRAINT [CAI_caID]
GO
This is the preview where I encountered the problem, it contains duplicate records:
Hope someone understand my explanation.
Sometimes GUIS have limitations (or not but you haven't discovered yet how all functionalities work). You can always add a unique constraint with ALTER TABLE:
ALTER TABLE [dbo].[clientaccess]
ADD CONSTRAINT Module_Client_UQ --- choose a name
UNIQUE (ModuleName, ClientAuthenticationId) ;
I am trying to set a foreign key relationship between an Order_Items table and Parts table. I want to link the parts to products in the Order_Items table via foreign key. I have no issues doing this with other tables.
Here is how the Order_Items table is defined:
CREATE TABLE [dbo].[Order_Items](
[order_id] [uniqueidentifier] NOT NULL,
[product_number] [varchar](50) NOT NULL,
[quantity_ordered] [int] NOT NULL,
[product_tested] [bit] NULL,
CONSTRAINT [PK_Order_Items] PRIMARY KEY CLUSTERED
(
[order_id] ASC,
[product_number] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
ALTER TABLE [dbo].[Order_Items] WITH CHECK ADD CONSTRAINT [FK_Order_Items_Orders] FOREIGN KEY([order_id])
REFERENCES [dbo].[Orders] ([order_id])
GO
ALTER TABLE [dbo].[Order_Items] CHECK CONSTRAINT [FK_Order_Items_Orders]
and Parts table:
CREATE TABLE [dbo].[Parts](
[part_number] [varchar](50) NOT NULL,
[product_number] [varchar](50) NOT NULL,
[part_description] [varchar](max) NULL,
[part_tested] [bit] NULL,
CONSTRAINT [PK_Parts_1] PRIMARY KEY CLUSTERED
(
[part_number] ASC,
[product_number] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
I have tried setting the unique constraint on both product_number columns, but I still get the error message in SQL Server 2005 Management Studio Express as:
"The columns in table 'Order_Items' do not match an existing primary key or UNIQUE constraint"
Question: if [product_number] in your Parts table can be made unique by a unique constraint - why isn't it the primary key by itself??
My gut feeling: [product_number] in Parts isn't really unique - only the combination of (part_number, product_number), which is the primary key, really is unique.
If you can create a UNIQUE INDEX on the product_number column alone, you should be able to create the FK constraint - try this:
CREATE UNIQUE INDEX UIX01_Parts ON dbo.Parts(product_number)
ALTER TABLE dbo.Order_Items
ADD CONSTRAINT FK_OrderITems_Parts
FOREIGN KEY(product_number) REFERENCES dbo.Parts(product_number)
Does it work? If not - what error to you get, and where??
If that doesn't work, and only (part_number, product_number) is truly unique, then you need to reference both columns in your foreign key constraint:
ALTER TABLE dbo.Order_Items
ADD CONSTRAINT FK_OrderItems_Parts
FOREIGN KEY(part_number, product_number)
REFERENCES dbo.Parts(part_number, product_number)
and of course, this also means you need to have both those columns in your Order_Items table in order to be able to make the foreign key constraint work.
Just as a side note: having a compound primary key of two VARCHAR(50) columns and making that a clustered index on your Parts table is anything but optimal. If ever possible, try to make one or both of those "numbers" really a numeric type - e.g. an INT column. Or if that is not possible, think about having a surrogate PartID column (INT, IDENTITY) on your Parts table - that would make the FK constraint easier, too!
In order for this relationship to work, the Parts table cannot have composite key. In other words, you need to use product_number as the primary key since it is the column that they both have in common. You currently have part_number and product_number as your primary key.
Once you make that change, this statement will work:
ALTER TABLE [dbo].[Order_Items] WITH CHECK
ADD CONSTRAINT [FK_Order_Items_Parts] FOREIGN KEY([product_number])
REFERENCES [dbo].[Parts] ([product_number])
I ended up restructuring my entire database to get this to work and streamlined the table connections.
I'm working with an existing SQL 2005 database that was not implemented with FK relationships between tables. I tried to add the relationships with a database diagram and my application immediately blew up trying to edit or insert any data that is tied to the new FK.
dbo.person [person_id | firstname | lastname | dateofbirth]
dbo.campaign [campaign_id | campaign_description]
dbo.disposition [disposition_id | disposition_description]
dbo.person_campaigns [person_campaign_id | person_id | campaign_id | disposition_id]
The person_campaigns table is where a person, campaign, and disposition are tied together. Can you please provide the appropriate SQL syntax for adding the proper FK relationships between these entities?
EDIT
CREATE TABLE [dbo].[person_campaigns](
[person_campaigns_id] [int] IDENTITY(1,1) NOT NULL,
[person_id] [int] NOT NULL,
[d_campaign_id] [int] NOT NULL,
[d_physician_disposition_id] [int] NULL,
CONSTRAINT [PK_person_campaigns] PRIMARY KEY CLUSTERED
(
[person_campaigns_id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
CREATE TABLE [dbo].[d_campaign](
[d_campaign_id] [int] IDENTITY(1,1) NOT NULL,
[name] [varchar](50) NULL,
[year] [int] NULL,
[isactive] [bit] NOT NULL,
CONSTRAINT [PK_d_campaign] PRIMARY KEY CLUSTERED
(
[d_campaign_id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
ALTER TABLE [dbo].[d_campaign] ADD CONSTRAINT [DF_d_campaign_isactive] DEFAULT ((1)) FOR [isactive]
GO
CREATE TABLE [dbo].[d_disposition](
[d_disposition_id] [int] IDENTITY(1,1) NOT NULL,
[name] [varchar](50) NULL,
[isactive] [bit] NOT NULL,
CONSTRAINT [PK_d_disposition] PRIMARY KEY CLUSTERED
(
[d_disposition_id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
ALTER TABLE [dbo].[d_disposition] ADD CONSTRAINT [DF_d_disposition_isactive] DEFAULT ((1)) FOR [isactive]
GO
CREATE TABLE [dbo].[person](
[person_id] [int] IDENTITY(1,1) NOT NULL,
[firstname] [varchar](30) NULL,
[lastname] [varchar](30) NULL,
[dateofbirth] [datetime] NULL
CONSTRAINT [PK__person__0BC6C43E] PRIMARY KEY CLUSTERED
(
[person_id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
the easiest way to do it is through the database diagram editor; do them one at a time and save the diagram to affect the tables after each connection is made. If it "blows up" it is most likely because the tables contain foreign-key values that do not exist; you'll have to clean these up first.
If you have to add them after the table is created the syntax is
create table person (person_id int primary key
,firstname varchar(10)
, lastname varchar(10)
, dateofbirth varchar(10))
create table campaign (campaign_id int primary key
, campaign_description varchar(10))
create table disposition (disposition_id int primary key
,disposition_description varchar(10))
create table person_campaigns(person_campaign_id int
,person_id int, campaign_id int ,disposition_id int)
go
alter table person_campaigns add Constraint
fk_person_campaigns_person_id
Foreign Key (person_id) References person(person_id)
GO
alter table person_campaigns add Constraint
fk_person_campaigns_campaign_id
Foreign Key (campaign_id) References campaign(campaign_id)
GO
alter table person_campaigns add Constraint
fk_person_campaigns_disposition_id
Foreign Key (disposition_id) References disposition(disposition_id)
GO
Suppose I had two tables that should have had a foreign key but did not. The first thing to do is check to see if there will be a data problem if I set a foreign key.
something like the below code would get you the records in the child table that do not have a match in the parent table.
select t2.FKField, t2.PKfield from table2 t2
left join Table1 t1 on t2.fkfield = t1.pkfield
where t1.pkfield is null
Once you can see what is wrong with the existing data, then you need to create a way to fix it. The fix will vary depending on what data you have that has no relationship to the Parent table and what the tables represent. Suppose your parent table contained a VIN number for automobiles as the PK. If your child table contains the cars that were worked on by the shop, you would want to fix the issue by adding the nonexisting VINS to the primary table becasue you wouldn't want to lose the history of what was worked on. There are other structures where you might want to simply delete the records that don't match in child table because they are meaningless. In other circumstances you might want to update those records to some default value (perhaps a customer in the customer table called unknown). In still other circumstances, you might need to go to audit tables or backups to find the value of the PK that was deleted without the associated child records being deleted. The actual way to fix this problem is highly dependent on what the data is used for and how important it is to retain all historical records. Since you should never delete any record that might be related to a financial transaction for legal (and accounting) reasons, you need to be most careful with those.
After fixing all the data, then you run the code to create the FK constraint.
Since I don't have SQL Server on this PC and I don't memorize the syntax, the easiest thing to do is to create two new test tables, create TableA with an ID field, TableB with a field that is a FK of TableA.ID, and then script out TableB to see the ADD CONSTRAINT syntax. Do this using SQL Server Management Studio via a database diagram.
However, if you were able to successfully create the FKs in a data diagram, and you only can't add or update records, I believe something else is wrong. Script out the person_campaigns table and post the code.