I'm trying out this database layout under MS SQL (de), with primary multicolomn key, but ....
Let's say table A, has primary KEY on the field PK_A
Let's say table B, has primary KEY on the field PK_B
Now table C, has fields ID_A and ID_B, defined as multicolomn primary key, referencing obviuosly to the PK_A and PK_B values.
NOW THE PROBLEM !! :(
Let present you table D , with his beautiful field ID_C. :)
How can I succed in referencing with the ID_C field the primary multicolomn key of table C ??
I' designing the whole thing with access97+mde, but dragging the PK key of table C (ID_A & ID_B) over the table D (ID_C) doesn't work !!
Hi,I have a history table with about 400 million rows, with a uniquecomposite nonclustered index on two columns (object id and time period)which is used for most of the queries into the table, and an identitycolumn for the clustered primary key.Many of my queries use correlated subqueries to pull unique historyrows from the history table for each of a set of objects from theobject table, for instance, pulling the earliest history row for eachobject in a set. These correlated subqueries reference the object tableand return the primary key of the history table, e.g.:select *from lp_object linner join lp_object_history hon h.lp_object_id = l.lp_idwhere l.lp_set_id = 'SOME_LITERAL'and h.lp_id = (select top 1 lp_idfrom lp_object_historywhere lp_object_id = l.lp_idand lp_some_column > 0order by lp_time_period)Now, if lp_some_column is not indexed, this query has no choice but toread the entirety of every single history row for every object in theset where lp_set_id = 'SOME_LITERAL', so that it can determine iflp_some_column > 0, and because the history table is clustered by theidentity column rather than the ID of the relevant object whose historywe're tracking, the reads take forever - they have to bop all aroundthe disk. The sets I deal with tend to have about 5K objects in themand about 200K associated history rows.I'm considering reclustering by the (object id, time period) index, butthen my queries will need an extra bookmark lookup step to get the rowdata from the identity value returned by the correlated subquery. Ithink it will still be faster, though, so I will probably build a copyof the table with the alternative clustering scheme to run someperformance tests.What I'm wondering is, if I were to dispense with the identity columnaltogether and replace it with a composite primary key of (object id,time period), would I be still be able to use my correlated subqueries?Because then there wouldn't be a single column that uniquely identifieseach row in the history table and I don't think SQL Server supportsmulticolumn correlated subqueries.Thanks for reading,Seth
Using the new referential integrity constraints that will be made available, will it allow us to manually define the relationships between entities even if there is no true foreign key constraints setup in the database?
Lets say we deleted the FK_Orders_Customers in Northwind between orders and customers.
I am new to MS SQL2005 but I have started working with it and found a difference between what MS Access and MS SQL will allow. I have a large DB with many tables but my problem relates to one specific issue. I have a table named tblAreaCodes which holds all area codes for the US. I have another table named tblSupplier where there are multiple colums such as name address etc. and three columns named phac, ph2ac, orderac, and faxac. All are the same type (Int) as is the Primary key in the tblAreaCode table. I have linked each of the columns in the tblSupplier table back to the primary in the tblAreaCode table. All is fine except I can not set the relationship to cascade update or delete. I am unsure what this means or how to proceed since this works and is allowed in MS Access. Any help and or direction would be greatly appreciated.
I used to work with little databases and throw everything into a table with no relation, and modify them all individually. Now I've learned about referential integrity, makes things a lot easier.
My question is, now what? Say I have a Customers table and an Orders table (to keep it simple). If custID is the primary key in customers, foreign key in orders, then if I want to insert into Orders, I need the custID. So those kinds of things I need to keep stored in a session state and insert them like that, correct?
Is there a way of finding the foreign keys for a table and therefore determine weather any referential integrity rules would be broken if a record was deleted?
For example. You have an author you want to delete, but that author has books. You call a procedure to delete the author. The stored procedure checks the foriegn keys, checks the tables and determines what is in them and if any tables have records that would be "orphaned" you return an error reporting what tables have the "would be orphaned" data in them.
It need to be fairly generic int he manner that it checks the foreign keys and the sub table data.
This is on behalf of a guy at work so "requirements" may change. ;)
hi guys, i was asked to drop some tables...but before dropping i was asked to check for referential integrity.. so where and how can i check this referential integrity????
Hihow to set the referential integrity between 2 tables using enterprisemanager (microsoft SQL SERVER).. i tried and the tab doesn't allow meto choose. pls.help.thankssree--chavasreedharMessage posted via http://www.exforsys.com for all your training needs.
I'm not sure about the way you enforce the referential integrity in a SQL server 6.5 database (I'm new to this environment). Does any one have an exemple. The doc I have is useless...Thanks
I am using SQL server 2000. I have a parent table 'MimeTypes' with primary key 'mimetype'. This is referenced as foreign key in table 'AssetTypes' as column 'BaseMimeType'. The referential constraint is simple : alter table AssetTypes add constraint FK_ASSETTYPES_REF_BASEMIMETYPE foreign key (BaseMimeType) references MimeTypes (MimeType) on update no action on delete no action;
I have FOR Update trigger on parent table ('MimeTypes') which is as follows:
CREATE TRIGGER trg_MimeTypes_update ON MimeTypes FOR UPDATE AS IF UPDATE(MimeType) BEGIN UPDATE AssetTypes SET BaseMimeType = (select MimeType from inserted) FROM AssetTypes as A JOIN deleted as d on A.BaseMimeType = d.MimeType END;
******** The problem is simple. I want to execute a update query on parent table ('MimeTypes') which modifies 'mimetype' value referenced by child. I dont want to include cascade option in constraint. When such query is executed error comes as : UPDATE statement conflicted with COLUMN REFERENCE constraint 'FK_ASSETTYPES_REF_BASEMIMETYPE'. The conflict occurred in database 'default.db', table 'AssetTypes', column 'BaseMimeType'. ***** Is there any way to do this?
I'm using Microsoft SQL Server Management Studio Express 9.00.2047.00and expriencing problems with setting referential integrity on a linktable. The tables' schema is as follows:-------------------------------------------------------------------CREATE TABLE competencies (CID bigint identity(1,1) CONSTRAINT pk_CID PRIMARY KEY,LockedBy bigint DEFAULT 0 NOT NULLCONSTRAINT fk_UserIDREFERENCES usr_info(userID)ON DELETE SET DEFAULTON UPDATE CASCADE)---------------------------------------------------------CREATE TABLE usr_info (userID bigint IDENTITY(0,1) CONSTRAINT pk_UID PRIMARY KEY,ActiveFlag bit default 0 NOT NULL, --(1='Yes', 0='No')FirstName varchar(100) default '' NOT NULL,LastName varchar(100) default '' NOT NULL)-------------------------------------------------------CREATE TABLE competency_hdr (fkCID bigint default 0 NOT NULLCONSTRAINT fkCID_chREFERENCES competencies(CID)ON DELETE CASCADEON UPDATE CASCADE,ApprovedBy bigint default 0 NOT NULLCONSTRAINT fkUserID_chREFERENCES usr_info(userID)ON DELETE SET DEFAULT -- NO delete if user is deletedON UPDATE CASCADE)--------------------------------------------------------When I execute the above I get the following error message.Msg 1785, Level 16, State 0, Line 1Introducing FOREIGN KEY constraint 'fkUserID_ch' on table'competency_hdr' may cause cycles or multiple cascade paths. SpecifyON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGNKEY constraints.Msg 1750, Level 16, State 0, Line 1Could not create constraint. See previous errors.Now, if i swap the fields around then the error message changes tothat of the fkCID field.Basically what I want is:when I delete a competency record I need all references to this recordto be deleted.when I delete a user I want to set the foreign key to zero (the recordmust remain on the database).Obviously there is something I'm missing here. Any advice, anyone?---------------------------------------------------------------Join Bytes! : Remove your pants to reply---------------------------------------------------------------
Hello every body,I need some clarification of concept regarding self referentialtables.consider we have a "Person" table that stores data about employees ofan organisation.in case a person change his name or any details we dont want to updateour database by loosing old information and adding new one. what weneed is to hold previous details as well as the new ones.theoratically for me its easy i will just add another row and linkthat row with one of the existing row. to do so i created a relationbetween the "Emp_id" column of "Person" table to itself. so one"Emp_id" could be related to another "Emp_id" in the same table.after doing so i dont know how can i indicate while inserting a recordthat this new record in linked with one of the previous records. meansin insert statement how the relation ship would be added.here i am not sure if i am thinking in the right direction or not aswe may need to add another table or another column to indicate therelation between old an new row. but if we have to add that new columnsay "old_Emp_id" in "Person" table then what does the relationshipbetween "Emp_id" with itself serves.thanksAli
Is it possible to define a referential constraint between two tables in two different databases (on two servers)? Or are there beter best practices methods/products to achieve this result.
Hi, I need to write a referential integrity trigger. I have two tables called Table1 and Table2. In both the tables i have common column called FieldA. Now i need to write a trigger, whenever i updates Table1 this trigger automatically needs to update a FieldA in Table2. Can anyone give me Code or suggestions , how to write this trigger. I am new to triggers. Thank you!
Hi, I need to write a referential integrity trigger. I have two tables called Table1 and Table2. In both the tables i have common column called FieldA. Now i need to write a trigger, whenever i updates Table1 this trigger automatically needs to update a FieldA in Table2. Can anyone give me Code or suggestions , how to write this trigger. I am new to triggers. Thank you! I know how to write a normal insert , update, delete triggers and using help from books online.. SO pls do it in useful.
I am inserting into a table that hold several foreign keys from several tables. I'm performing this via a client (VB) and I only how to capture the error, but unable to determine which column/field is the one that violates referential integrity.
I have a lookup table called States, I have multiple other tables that use this lookup table, but I can only relate to one other table. My question is if I change a state name how do I enforce that change to the other tables that CANT be related? I know it is a design flaw and need some kind of joining table. I am having difficulty understanding and incorporating first normal form in my database. Here is what i have so far.
im having problems deleting rows in a reference table. is there any tools which tables to delete first before deleting the rows in the table which contains the primary key?
i have a lot of tables let say over 300 so its hard for me to guess which comes first... what should i keep in mind deleting rows with a referential integrity?
Two ways to do this... Creating the constraints when creating the data model OR using SQL to use the 'reference' constraint. Does 2005 provide any other automated method of creating the Primary Key - to Foreign key constraints without writing the SQL to do this?
Hello Everyone. I'm trying to set a procedural referential integrity on a table, files, which references to table users (a file is created by a user but one user can have more than one file). Here, given that I can't create a referential integrity ON DELETE SET NULL (the reason il long to explain so just don't care about it), I would like to emulate the RI with a trigger.
On deleting a user the files associated to him have their IDUser set to null. I have a problem, this is the trigger:
CREATE TRIGGER PRI_FilesOnUsers
ON Files
INSTEAD OF DELETE
AS
-- When a user is deleted the files must have no user associated, set IDUser to null
UPDATE Files
SET IDUser = NULL
WHERE IDUser = ?????????????????????????????????????????????????????
GO
WELL what do I heve to put there, how can i retrieve the values of the fields of the record that the user tried to delete?????Help me thanks
Just wondering what would be the normal or more efficient practice to insert/update a record.
1. Check for existence of primary record (using SELECT in stored procedure) 2. Capture error and handling
My problem is that I try to execute an stored procedure from a VB client.. but unable to capture the errors in SP, it just prompts the error and thats it, not responding to my "SELECT @err = @@ERROR" after the insert statement.
so now, I'm thinking of capturing the error on the client (which I am able to do) and handle it from there.. or to make sure that RI is enforced by 'searching' for Pks in the primary tables before executing the INSERT statement in my stored procedure.
I'm designing a database to store information about jobs that are in progress at a property. More than one job can be in progress at a property at one time and each different kind of job can contain different data, although they all share some common fields such as StartDate.
So I have a table that stores the property details PropertyDetails:
*ID PropertyAddress PropertyPostCode
Then I have a table that stores all of the jobs' shared details:
*PropertyID *JobID - These three make up a compound primary key *JobType StartDate EndDate
Then I have individual tables for each of the Jobs, for example BuildingWork:
*JobID BuildingContractor InsuranceCompany
Which works great, and enables me to query all basic job details from one table (JobDetails) rather than multiple tables for every job type.
BUT: I don't know how to enforce the referential integrity of the database. Obviously I can use a constraint to cascade deletes from the PropertyDetails table to the JobDetails table through the PropertyID, but there doesn't appear to then cascade the deletes from the JobDetails table to the individual Job tables as JobDetails has no idea what tables are there.
If I store the relevant individual table name as the JobType in the JobDetails table, could I use a trigger to somehow delete the related record from that table?
