SQL - Cascading Delete, Or Delete Trigger, Maintaining Referential Integrity - PLEASE HELP ME!!!
Nov 13, 2006
I am having great difficulty with cascading deletes, delete triggers and referential integrity.
The database is in First Normal Form.
I have some tables that are child tables with two foreign keyes to two different parent tables, for example:
Table A
/
Table B Table C
/
Table D
So if I try to turn on cascading deletes for A/B, A/C, B/D and C/D relationships, I get an error that I cannot have cascading delete because it would create multiple cascade paths. I do understand why this is happening. If I delete a row in Table A, I want it to delete child rows in Table B and table C, and then child rows in table D as well. But if I delete a row in Table C, I want it to delete child rows in Table D, and if I delete a row in Table B, I want it to also delete child rows in Table D.
SQL sees this as cyclical, because if I delete a row in table A, both table B and table C would try to delete their child rows in table D.
Ok, so I thought, no biggie, I'll just use delete triggers. So I created delete triggers that will delete child rows in table B and table C when deleting a row in table A. Then I created triggers in both Table B and Table C that would delete child rows in Table D.
When I try to delete a row in table A, B or C, I get the error "Delete Statement Conflicted with COLUMN REFERENCE". This does not make sense to me, can anyone explain? I have a trigger in place that should be deleting the child rows before it attempts to delete the parent row...isn't that the whole point of delete triggers?????
This is an example of my delete trigger:
CREATE TRIGGER [DeleteA] ON A
FOR DELETE
AS
Delete from B where MeetingID = ID;
Delete from C where MeetingID = ID;
And then Table B and C both have delete triggers to delete child rows in table D. But it never gets to that point, none of the triggers execute because the above error happens first.
So if I then go into the relationships, and deselect the option for "Enforce relationship for INSERTs and UPDATEs" these triggers all work just fine. Only problem is that now I have no referential integrity and I can simply create unrestrained child rows that do not reference actual foreign keys in the parent table.
So the question is, how do I maintain referential integrity and also have the database delete child rows, keeping in mind that the cascading deletes will not work because of the multiple cascade paths (which are certainly required).
Hope this makes sense...
Thanks,
Josh
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Aug 17, 2005
I need to implement my cascading deletes on a SQL database. Is it better (performance/reliablility-wise) to use the Foreign Key Cascading Deletes or to just write my own triggers to do the deletes?I was hoping someone had experimented and found which works best.
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Oct 3, 2005
hello guysi am using a table that its secondary key connected to its primary key...and as sql server 2000 doesnt allow cascade delete fore such,i had to write a trigger myselfso i wrote the following triggerCREAT TRIGGER nameON tableFOR DeleteASBEGINIF @@ROWCOUNT >0Delete from table where table.parentID in (select sortID from deleted);ENDthen i went to the table and i tried to delete...and it gave me an error....that there are records that have there parentID= sortID of the table i am trieng to delete...so i deleted the relationship...and kept the triggerand now ...when i delete one...it deletes one level down....but not more....i mean when i delete sortID=4it deletes all the records that has parentID=4...and NOT more..whereas my aim was to have it recursive not to have records lost in my databasehope i explained good as much as i hope to find an answer soon...a clear one...and thanks in advanced...
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Nov 10, 1998
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
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Oct 4, 2000
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!
---Ram
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Oct 4, 2000
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.
---Ram
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Mar 16, 2007
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.
Or is this ability available now?
Thank for your time.
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Jun 6, 2008
Hi, I tried to delete a record in tblA which has an ID in tblB, i got error msg saying referential problem, please tell me what should i do? thanks.
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Nov 8, 2006
I use SQL Server 2005I have tables tblUserData, tblUsersAndGuestbook, tblGuestbooktblUserdata contains:UserCode intUsername nvarchar(50)tblUsersAndGuestbook contains:Usercode int (FK to tblUserData)GBEntryCode inttblGuestbookGBEntryCode int (FK to tblUsersAndGuestbook)GBText textNow...if I delete a user in tblUserData I want to also delete the entries in tblUsersAndGuestbook AND in tblGuestbook.I've heard something about cascading delete, but how can i configure that in my database?Or do I manually need to delete all entries from code?
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Jun 4, 2001
Hi,
I read all the existing material in SWYNK but still am not clear on the following question.
What is the best way to perform Cascading actions (Delete & Update) with foreign Key Constraints declared? We are using SQL Server 7.0
thanks
Rozina
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Sep 14, 2004
Procedure spDeleteRows
/*
Recursive row delete procedure.
It deletes all rows in the table specified that conform to the criteria selected,
while also deleting any child/grandchild records and so on. This is designed to do the
same sort of thing as Access's cascade delete function. It first reads the sysforeignkeys
table to find any child tables, then deletes the soon-to-be orphan records from them using
recursive calls to this procedure. Once all child records are gone, the rows are deleted
from the selected table. It is designed at this time to be run at the command line. It could
also be used in code, but the printed output will not be available.
*/
(
@cTableName varchar(50), /* name of the table where rows are to be deleted */
@cCriteria nvarchar(1000), /* criteria used to delete the rows required */
@iRowsAffected int OUTPUT /* number of records affected by the delete */
)
As
set nocount on
declare @cTab varchar(255), /* name of the child table */
@cCol varchar(255), /* name of the linking field on the child table */
@cRefTab varchar(255), /* name of the parent table */
@cRefCol varchar(255), /* name of the linking field in the parent table */
@cFKName varchar(255), /* name of the foreign key */
@cSQL nvarchar(1000), /* query string passed to the sp_ExecuteSQL procedure */
@cChildCriteria nvarchar(1000), /* criteria to be used to delete
records from the child table */
@iChildRows int /* number of rows deleted from the child table */
/* declare the cursor containing the foreign key constraint information */
DECLARE cFKey CURSOR LOCAL FOR
SELECT SO1.name AS Tab,
SC1.name AS Col,
SO2.name AS RefTab,
SC2.name AS RefCol,
FO.name AS FKName
FROM dbo.sysforeignkeys FK
INNER JOIN dbo.syscolumns SC1 ON FK.fkeyid = SC1.id
AND FK.fkey = SC1.colid
INNER JOIN dbo.syscolumns SC2 ON FK.rkeyid = SC2.id
AND FK.rkey = SC2.colid
INNER JOIN dbo.sysobjects SO1 ON FK.fkeyid = SO1.id
INNER JOIN dbo.sysobjects SO2 ON FK.rkeyid = SO2.id
INNER JOIN dbo.sysobjects FO ON FK.constid = FO.id
WHERE SO2.Name = @cTableName
OPEN cFKey
FETCH NEXT FROM cFKey INTO @cTab, @cCol, @cRefTab, @cRefCol, @cFKName
WHILE @@FETCH_STATUS = 0
BEGIN
/* build the criteria to delete rows from the child table. As it uses the
criteria passed to this procedure, it gets progressively larger with
recursive calls */
SET @cChildCriteria = @cCol + ' in (SELECT [' + @cRefCol + '] FROM [' +
@cRefTab +'] WHERE ' + @cCriteria + ')'
print 'Deleting records from table ' + @cTab
/* call this procedure to delete the child rows */
EXEC spDeleteRows @cTab, @cChildCriteria, @iChildRows OUTPUT
FETCH NEXT FROM cFKey INTO @cTab, @cCol, @cRefTab, @cRefCol, @cFKName
END
Close cFKey
DeAllocate cFKey
/* finally delete the rows from this table and display the rows affected */
SET @cSQL = 'DELETE FROM [' + @cTableName + '] WHERE ' + @cCriteria
print @cSQL
EXEC sp_ExecuteSQL @cSQL
print 'Deleted ' + CONVERT(varchar, @@ROWCOUNT) + ' records from table ' + @cTableName
--------
The above code is good .. but has limitation...throws an error:
Server: Msg 217, Level 16, State 1, Procedure spDeleteRows, Line 58
Maximum stored procedure, function, trigger, or view nesting level exceeded (limit 32).
Can anyone out there suggest a better way of implementing on a database without a limitation of levels.. we are talking about a HUGE DB with lots of table and FK referentials..
Please advice.. or solve the problem..
Thank you
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Jul 20, 2005
I use cascading delete on my SQL Server Database. I am experiencing along query time on my highest level delete, 10 minutes. If I deletefrom each table manually and then delete the parent, I will usually bedone in less than a minute. Any suggestions?
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Aug 18, 2007
If we want to maintain the data in relationships.
There are two ways to do it.
1. Auto (Like Cascading Update And Delete)
2. Manually (Like In Stored Procedures)
I read an intresting article
http://imar.spaanjaars.com/QuickDocId.aspx?quickdoc=419
In this article Imar has choosen the second way (Manually).
And when I talk to Imar.
He said, "Cascading deletes would have worked equally well in this situation. However, I personally don't like them too much. I am much rather in control, enabling me to delete what I want and when I want it. I could, for example, keep certain data for "time travelling scenarios" (e.g. the state things were in some time ago) or I might want to keep it for other purposes."
Can any one help me to choose the better one.
Waiting for helpful replies.
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Jul 15, 1999
Is it possible to perform a cascading delete and update using TRIGGERS on a table referenced by a foreign key constraint.?To be more specific.. if the primary key is deleted does the delete trigger on the primary table deletes the record in the foreign key table or does it return an error??
if possible please send us the T SQL Statements .
Thanks in Advance
Geenu
Ajaz Dawre
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Nov 16, 2006
Edit: Sorry This is OSQL.What I use as my query is:"DELETE FROM timerecord WHERE Actual_Time_In LIKE '11.12.2006%'"The row of Actual_Time_In is formatted with Date and time (MM.DD.YYYY HH:MM:SS) sometimes there are ten records and I'd rather not have to remove them from the table one at a time. However, even though I have a record that is '11.12.2006 22:43:00' my delete doesn't work osql states I have 0 rows affected.This is only MSDE so I don't have anyother way to open the table.Sometimes these records have other records that reference them. Is there anyway to do a cascading delete without it getting to complex?Thanks of all your help, I am just a tech support guy beating his head against a wall..
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Feb 16, 2008
This function will generate all DELETE statements in correct order to perform a CASCADING delete.
For self-joined tables, it will generate the T-SQL code to "unwind" the table, also in correct order!CREATE FUNCTION dbo.fnCascadingDelete
(
@Schema NVARCHAR(128) = NULL,
@Table NVARCHAR(128) = NULL
)
RETURNS@Return TABLE
(
RowID INT PRIMARY KEY CLUSTERED,
IsSelfJoin TINYINT NOT NULL,
HasPk TINYINT NOT NULL,
[SQL] NVARCHAR(4000) NOT NULL
)
AS
BEGIN
DECLARE@Constraints TABLE
(
RowID INT NOT NULL,
Indent SMALLINT NOT NULL,
[Catalog] NVARCHAR(128) NOT NULL,
[Schema] NVARCHAR(128) NOT NULL,
[Table] NVARCHAR(128) NOT NULL,
[Column] NVARCHAR(128),
pkCatalog NVARCHAR(128),
pkSchema NVARCHAR(128),
pkTable NVARCHAR(128),
pkColumn NVARCHAR(128),
pkType NVARCHAR(128),
pkSize INT,
IsSelfJoin TINYINT NOT NULL,
HasPk TINYINT NOT NULL
)
INSERT@Constraints
(
RowID,
Indent,
[Catalog],
[Schema],
[Table],
[Column],
pkCatalog,
pkSchema,
pkTable,
pkColumn,
pkType,
pkSize,
IsSelfJoin,
HasPk
)
SELECTRowID,
Indent,
[Catalog],
[Schema],
[Table],
[Column],
pkCatalog,
pkSchema,
pkTable,
pkColumn,
pkType,
pkSize,
SelfJoin,
CASE
WHEN [Column] IS NULL THEN 0
ELSE 1
END
FROMdbo.fnTableTree(@Schema, @Table)
IF @@ROWCOUNT = 0
RETURN
DECLARE@SQL TABLE
(
ID INT IDENTITY(1, 1),
RowID INT PRIMARY KEY CLUSTERED,
IsSelfJoin TINYINT NOT NULL,
HasPk TINYINT NOT NULL,
[SQL] NVARCHAR(4000) NOT NULL
)
DECLARE@Indent SMALLINT,
@RowID INT,
@ID INT,
@TSQL NVARCHAR(4000),
@RowSQL NVARCHAR(4000),
@EndSQL NVARCHAR(4000),
@pkColumn NVARCHAR(128),
@IsSelfJoin TINYINT,
@HasPk TINYINT
DECLARE@Unwind TABLE
(
RowID INT NOT NULL,
StepID INT IDENTITY(0, 1) PRIMARY KEY NONCLUSTERED,
[SQL] NVARCHAR(4000)
)
WHILE NOT EXISTS (SELECT * FROM @SQL WHERE RowID = 1)
BEGIN
SELECT TOP 1@RowID = c.RowID,
@ID = c.RowID,
@Indent = c.Indent,
@TSQL = N'',
@EndSQL = N'',
@IsSelfJoin = c.IsSelfjoin,
@HasPk = c.HasPk
FROM@Constraints AS c
LEFT JOIN@SQL AS s ON s.RowID = c.RowID
WHEREs.RowID IS NULL
ORDER BYc.Indent DESC,
c.RowID DESC
WHILE @ID > 0
BEGIN
IF @Indent = 0
SELECT@RowSQL = N'DELETE t' + CAST(@RowID AS NVARCHAR(12)),
@RowSQL = @RowSQL + N' FROM ' + QUOTENAME(c.[Catalog]) + N'.' + QUOTENAME(c.[Schema]) + N'.' + QUOTENAME(c.[Table]) + N' AS t' + CAST(@ID AS NVARCHAR(12)),
@EndSQL = N' WHERE t' + CAST(@ID AS NVARCHAR(12)) + '.' + QUOTENAME(COALESCE(c.[Column], '%0')) + N' = ''%1''',
@IsSelfJoin = @IsSelfJoin | c.IsSelfJoin
FROM@Constraints AS c
WHEREc.RowID = @ID
ELSE
SELECT@RowSQL = N' INNER JOIN ' + QUOTENAME(c.[Catalog]) + N'.' + QUOTENAME(c.[Schema]) + N'.' + QUOTENAME(c.[Table]),
@RowSQL = @RowSQL + N' AS t' + CAST(@ID AS NVARCHAR(12)) + N' ON t' + CAST(@ID AS NVARCHAR(12)) + N'.' + QUOTENAME(c.[Column]),
@pkColumn = QUOTENAME(c.pkColumn),
@IsSelfJoin = @IsSelfJoin | c.IsSelfJoin
FROM@Constraints AS c
WHEREc.RowID = @ID
SELECT TOP 1@ID = c.RowID,
@Indent = c.Indent,
@RowSQL = @RowSQL + N' = t' + CAST(c.RowID AS NVARCHAR(12)) + N'.' + @pkColumn,
@IsSelfJoin = @IsSelfJoin | c.IsSelfJoin
FROM@Constraints AS c
WHEREc.RowID < @ID
AND c.Indent < @Indent
ORDER BYc.Indent DESC,
c.RowID DESC
IF @@ROWCOUNT = 0
SET@ID = 0
SET@TSQL = @RowSQL + @TSQL
END
INSERT@SQL
(
RowID,
IsSelfJoin,
HasPk,
[SQL]
)
VALUES(
@RowID,
@IsSelfJoin,
@HasPk,
@TSQL + @EndSQL
)
IF @IsSelfJoin = 1
BEGIN
DECLARE@Yak NVARCHAR(160),
@Catalog NVARCHAR(128),
@Column NVARCHAR(128)
SELECT@Yak = pkType + COALESCE('(' + CAST(pkSize AS NVARCHAR(12)) + ')', ''),
@Catalog = [Catalog],
@Schema = [Schema],
@Table = [Table],
@Column = [Column],
@Catalog = [Catalog],
@Table = [Table],
@pkColumn = pkColumn
FROM@Constraints
WHERERowID = @RowID
SET@RowSQL = 'DECLARE@Lvl INT
SET@Lvl = 0
DECLARE@Stage TABLE (RowID INT IDENTITY(0, 1), Lvl INT, RowKey ' + @Yak + ')
INSERT @Stage (Lvl, RowKey) '
+ REPLACE(@TSQL + @EndSQL, 'DELETE t' + CAST(@RowID AS NVARCHAR(12)) + '', 'SELECT 0, t' + CAST(@RowID AS NVARCHAR(12)) + '.' + QUOTENAME(@Column) + '')
+ ' WHILE @@ROWCOUNT > 0
BEGIN
SET@Lvl = @Lvl + 1
INSERT@Stage (Lvl, RowKey)
SELECT@Lvl,
t.' + QUOTENAME(@pkColumn) + '
FROM' + QUOTENAME(@Catalog) + '.' + QUOTENAME(@Schema) + '.' + QUOTENAME(@Table) + ' AS t
INNER JOIN@Stage AS s ON s.RowKey = t.' + QUOTENAME(@Column) + '
AND s.Lvl = @Lvl - 1
LEFT JOIN@Stage AS cr ON cr.RowKey = t.' + QUOTENAME(@pkColumn) + '
WHEREcr.RowKey IS NULL
END
SELECT ''DELETE FROM ' + QUOTENAME(@Catalog) + '.' + QUOTENAME(@Schema) + '.' + QUOTENAME(@Table) + ' WHERE ' + QUOTENAME(@pkColumn) + ' = '' + QUOTENAME(RowKey, '''''''')
FROM @Stage
WHERE RowID > 0
ORDER BY RowID DESC'
INSERT@Unwind
(
RowID,
[SQL]
)
VALUES(
@RowID,
@RowSQL
)
END
END
INSERT@Return
(
RowID,
IsSelfJoin,
HasPk,
[SQL]
)
SELECTs.ID,
s.IsSelfJoin,
s.HasPk,
CASE
WHEN u.RowID IS NULL THEN s.[SQL]
ELSE u.[SQL]
END
FROM@SQL AS s
LEFT JOIN@Unwind AS u ON u.RowID = s.RowID
ORDER BYs.ID,
u.StepID
RETURN
ENDE 12°55'05.25"
N 56°04'39.16"
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Aug 11, 2001
Question:
What is used to enforce referential integrity ?
Answer: Triggers; Foriegn Keys.
what is Foreign Keys ?
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Oct 17, 2001
How do you enforce referential integrity in SQL between tables?
Thanks.
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Feb 26, 2008
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?
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Oct 26, 2004
Hi guys,
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. ;)
Anyone got some ideas??
Cheers,
Shaun
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Feb 1, 2008
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????
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Dec 23, 2005
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.
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Apr 21, 2008
What ate the method/techniques i can use for enforcing referential integrity, Without using foreign key constraints ?
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Jun 3, 2006
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---------------------------------------------------------------
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Aug 11, 2000
How I do, in SQL SERVER 7.0, referential integrity (Foreign Key constraints) between tables storaged in differents databases?.
Thank for any help.
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Oct 4, 2004
Hi All,
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.
Any one can shed some light here? Many thanks!
Cyherus
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Oct 12, 2004
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.
Example:
Table 1
========|============|=============|========|
CustomerID BillingAddressID ShippingAddressID OtherFields
========|============|=============|========|
Table 2
===========|======|========|
BillingAddressID StateID OtherFields
===========|======|========|
Table 3
=============|======|========|
ShippingAddressID StateID OtherFields
=============|======|========|
Table 4
======|====|
StateID Name
======|====|
How do I relate table 4 with table 2 & 3 for referential integrity? Or create a joiner table?
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Dec 7, 2006
hi there!
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?
thank...
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Aug 24, 2006
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?
Thx
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Nov 19, 2007
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
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Jul 7, 2007
Hi,
How could I define referential integrity using FK constraint which allow me to have empty string/ZERO number instead of NULL value ?
Thank you
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Apr 12, 2007
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?
Littlecharva
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Apr 10, 2006
Is there a way to disable referential integrity on all destination tables for an import?
Thanks.
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