Junction Table/ Many To Many Relationships
May 9, 2007
I am trying to update 2 tables at the same time by adding new records to them and then making sure that they are related on my junction table?
Table1
packageID
Packagename
Table2 (JunctionTable)
PackageID
JobID
Table3
JobID
JobName
And I want to create a new package and new Job Name at the same time I would need to make multiple insert statements
First take care of the new Package
INSERT INTO Table1 (PackageName) Value (@PackageName)
Then Take Care of the JobName
INSERT INTO Table3 (JobName) Value (@JobName)
Finally marry the two together
but how?
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Feb 17, 2006
I have two tables. A table called users (content speaks by it self) and a table called groups.
Since i want every user to be able to be a member of several groups and, of course, a group to have several users i have made a junction table called jt.
The junction table contains userId's and groupId's according to the user-group bindings. The primary key(identity) in the junction table is a int named jtId.
Now i want to take out all posts from the junctiontable and the corrresponding userName (s) from the users-table and the corresponding groupName from the groups-table.
Can somebody please help me to make a SQL command that will di that for me. I have tried with INNER JOIN and several SELECTS in the same command.
Thanks in advance, Greetings from Esben
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Sep 23, 2007
Looking for some help here, so thanks for any input. I'm a painfully new newbie to SQL scripting.Situation:
I have a simple database to handle an organization's events. Those
events are categorized and may have more than one category assigned to
each event. I need a maintenance Web Form to update their events.Set
Up (so far): I have a CATEGORIES table. It has an auto incrementing UID
and a Category name field. This table will be updated so infrequently,
I plan to update it manually (no need for a maintenance Web Form). Next
is the EVENTS table. It also has an auto incrementing UID along with
several fields (Title, Location, DateTime, etc.). The junction table is
named jEVENTSCATEGORIES. It has its own auto incrementing UID along
with 2 fields named for the primary keys (UIDs) in the other 2 tables
(EventsID and CategoryID).Goal: On the Web Form, I have a
CheckBoxList control that's populated by the CATEGORIES table. One or
more categories can be checked for each event. I have a FormView
control that allows Edits and Inserts.Need: I need to know the
INSERT statement(s) required to insert a new record in the EVENTS table
and then to update one or more rows in the junction table
(jEVENTSCATEGORIES).My Assumptions: I know how to create
SELECTs and INSERTs and whatnot, but I'm not certain how to create a
second INSERT statement that is based on a variable (or output) from a
previous action. So any help would be MUCH appreciated. Thanks for your
time!
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Jan 30, 2008
Hi i have a junction table(UserGroups) which is linking my users table with my groups table, however when the information is coming back in the format below, instead i want the group names to appear in only one field, instead of repeating the same data, could someone please tell me what i need to change
UserName: Edwin CarolsUserAge: 28JobTitle: ManagerGroupName: MUFC
UserName: Edwin CarolsUserAge: 28JobTitle: ManagerGroupName: AFC
Below is my SQL statement;
SELECT Users.UserName,Users.UserAge, Users.JobTitle, Groups.GroupName FROM Users INNER JOIN UserGroups ON Users.UserID = UserGroups.UserID INNER JOIN Groups ON UserGroups.GroupID = Groups.GroupID WHERE (Users.UserID = '5')
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May 5, 2014
Why do we need a junction table in a many to many relationship? Why can't everything be in just 2 tables?
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Jul 20, 2005
As an example, I am building an authentication mechanisim that will usedata in the 3 left tables to determine rights to objects in adestination table, diagrammed below. In this structure, multiplerecords in the left tables will point to multiple records in the righttable. Normally, I would approach this problem using junction tables(LeftID, RightID) to create many-to-many joins.However, given the structure of each table is nearly identical (as faras the linking IDs are concerned), I could also use a single junctiontable with columns for each available table ID (LeftID1, LeftID2,LeftID3, RightID). In this table, only two IDs would be utilized perrow (LeftIDx -> RightID).In both designs, the needed rights information is returned from fairlysimple views, thus the end result is equivalent. The advantage to thesecond, multi-ID junction table design, is a simpler databasestructure. However, never using this approach before, I am unsure ofthe potential future performance impacts.Any significant downsides to this second design? Examples of anabbreviated structure follow:Data Tables-----------LeftTable1LeftID1 (int)Data1LeftTable2LeftID2 (int)Data2LeftTable3LeftID3 (int)Data3DestinationTableRightID (int)DataLinking tables option 1-----------------------JunctionTable1LeftID1RightIDJunctionTable2LeftID3RightIDJunctionTable3LeftID3RightIDLinking table option 2----------------------JunctionID1 (int)ID2 (int)ID3 (int)DestinationID (int)
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Feb 28, 2008
Hi i have a junction table(UserGroups) which is linking my "users" table with my "groups" table, however when the information is coming back in the format below, instead i want the group names to appear in only one field, instead of repeating the same data, could someone please tell me what i need to change.
UserName: Edwin CarolsUserAge: 28JobTitle: ManagerGroupName: MUFC
UserName: Edwin CarolsUserAge: 28JobTitle: ManagerGroupName: AFC
Below is my SQL statement;
SELECT Users.UserName,Users.UserAge, Users.JobTitle, Groups.GroupName FROM Users INNER JOIN UserGroups ON Users.UserID = UserGroups.UserID INNER JOIN Groups ON UserGroups.GroupID = Groups.GroupID WHERE (Users.UserID = '5')
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Mar 1, 2008
Hi i have a junction table(UserGroups) which is linking my "users" table with my "groups" table, however when the information is coming back in the format below, instead i want the group names to appear in only one field, instead of repeating the same data, could someone please tell me what i need to change.
UserName: Edwin Carols
UserAge: 28
JobTitle: Manager
GroupName: MUFC
UserName: Edwin Carols
UserAge: 28
JobTitle: Manager
GroupName: AFC
Below is my SQL statement;
Code:
SELECT Users.UserName,Users.UserAge, Users.JobTitle, Groups.GroupName FROM Users INNER JOIN UserGroups ON Users.UserID = UserGroups.UserID INNER JOIN Groups ON UserGroups.GroupID = Groups.GroupID WHERE (Users.UserID = '5')
And my table structure is like;
Users; UserID, UserName, UserAge
Groups; GroupID, GroupName
UserGroups; UserGroupID, UserID, GroupID
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Nov 30, 2005
Hi all,
This is a bit of a general question regarding SQL Server link tables that i hope someone can find the time to answer.
I am looking for the best practice. If I have 3 tables
1) tblCompetition
2) tblTeams
3) tblTeamsInCompetition (this is the link table)
I know the link table should have a related CompetitionID and TeamID,
but should the link table also have a primary key that is an identity
autoincrement by 1 just as you would with the other two tables. In
Access I have never done this, however in SQL Server I have read that
you should do this (but now I can't find the documentation again which
prompts me to ask the question here).
Thanks for taking the time to answer this question.
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Oct 10, 2007
Hello,
This seems like such a simple problem but I am new developer even through I have been on the administration end of things for some time. I will go into more detail about my tables and there relationships below. Anyway, I am trying to create a many-to-many relationship within ms sql server 2005. I have created both of my primary tables and also a junction table per the directions on microsoft's website all per ms's instructions as stated here...
http://msdn2.microsoft.com/en-us/library/ms178043.aspx
At then end of these instruction it states as a NOTE: The creation of a junction table in a database diagram does not insert data from the related tables into the junction table. For information about inserting data into a table, see How to: Create Insert Results Queries (Visual Database Tools).
http://msdn2.microsoft.com/en-us/library/ms189098.aspx
and these directions do not go into detail on how to do an insert on a junction table. And I cant find out how to do this anywhere on the internet... I did create a T-SQL INSERT statement in a trigger as listed below but I end up getting an error AS LISTED BELOW....
Here is how I set everything up...
PetitionSet table consists of:
PetitionSetID int auto-increment primary key
PetitionSetName varchar(50) no nulls
PetitionSetScope varchar(50) no nulls
the Petition table consists of:
PetitionID int auto-increment primary key
PetitionSetID int no nulls
PetitionName varchar(50) no nulls
the SetToPetitionJunction table consists of:
PetitionSetID int
PetitionID int
And, there is a composite key made up of both the PetitionSetID and PetitionID fields.
I have created the foreign key relationships with DEFAULT VALUES from the SetToPetitionJunction table to each column's respective corresponding column in each of the tables: PetitionSet and Petition.
The trigger is on the Petition table and it has the following code:
set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go
-- =============================================
-- Author: Name
-- Create date:
-- Description:
-- =============================================
ALTER TRIGGER .[SetToPetitionJunctionTrigger]
ON .[dbo].[Petition]
AFTER INSERT
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
INSERT INTO SetToPetitionJunction
(PetitionID, PetitionSetID)
SELECT Petition.PetitionID, PetitionSet.PetitionSetID
FROM Petition INNER JOIN
PetitionSet ON Petition.PetitionSetID = PetitionSet.PetitionSetID
END
I have created an asp.net 2.0 front end to insert values into the PetitionSet table and the Petition Table. And in the detailsview for the Petition table I manually insert the PetitionSetID field to the number that corresponds to an auto-generated number on the primary key of the PetitionSet table. So I am maintaining referential integrity...
The first time it works and inserts one record in the Junction table containing the PetitionSetID from the PetitionSet table and the PetitionID from the petition table.
Then when I try to add in another petition for the same petition set number just like I did the first time and then I get this error...
Violation of PRIMARY KEY constraint 'PK_SetToPetitionJunction'. Cannot insert duplicate key in object 'dbo.SetToPetitionJunction'.
The statement has been terminated.
David
All Rights Reserved in All Media
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May 1, 2008
Hello specialists.
Maybe this is the wrong formum but I've got a question for which you probably have the answer, i hope.
Situation
------------
John is member of Group_A and Group_B
Bill is member of Group_B and Group_C
Allison is member of Group_A and Group_E
How can I create a query to input Allisons username into table 1 and groupmembership into table 2. Also updating the relationship within junction-table3 must be done automaticaly. I want to avoid duplicate records.
The final situation I want is given in red text.
The relationships between the tables are as follows
-------------------------------------------------------------
Table1 (PK)ID-Userinfo [ONE] <------------> [MANY] Table3 ID-Userinfo
Table3 (PK)ID-GroupInfo [MANY] <------------> [ONE] Table2 (PK)ID-GroupInfo
Table1: UserInfo
------------------------------
(PK)ID-Userinfo UserName
1 John
2 Bill
3 Allison
Table2: GroupInfo
------------------------------
(PK)ID-GroupInfo GroupName
1 Group_A
2 Group_B
3 Group_C
4 Group_E
Table3: MemberOf
------------------------------
(PK)ID-MemberOf ID-UserInfo ID-GroupInfo
1 1 1
2 1 2
3 2 2
4 2 3
5 3 1
6 3 4
I hope you can help me cracking this nut.
Thx in advance. Greetings Fred
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Oct 26, 2006
Can Somebody please show me how to acheive this, using the order details in Northwinddatabase or any other good example. as much details as possible. Many Thanks!
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Jul 20, 2005
Hi,Does anyone have any suggestions on the best to go about enforcing arelationship between two tables that exist within separate databaseson the same SQL Server instance.
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Jul 20, 2005
I have the tables tblEmployees and tblProjects.tblProjects has one column called Percentagetime, to hold the percentage oftime by an employee for a project.My Question : Why should we introduce a 3rd table calledtblProjectsAndEmployees?tblProjectsAndEmployees will have1)EmployeeNumber(PrimaryKey in tblEmployees)2)ProjectNumber(Primary key in tblProjects)3)PercentageTimeHaving only the tblEmployees and tblProjects is not sufficient?Kind Regards,Vinodh Kumar P
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May 19, 2008
Hi,
I'm working on a database for which I require to have a lot of relations from my Persons table to other tables. I will need my primary key in those other tables: about 10 to 15 tables, to be able to relate to my persons data.
I believe this means I have 10 to 15 clustered indexes on this table.
Is this the right way of working? I know too many of this relations to other tables will have impact on performance concerning insert and updates.
But I noticed in the adventureworks example it works just this way for the products table.
What is the max limit of this kind of relations? (for reasonably good performance)
Should I use triggers instead? - for those with the least user interaction?
Thanks in advance,
Mike
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Jan 26, 2004
Hello,
I am looking to print the table structure of a Microsoft SQL Server 7 database through the Enterprise Manager Utility. I would like to print it to a plotter but the print options in the Enterprise Manager are inadequate. I believe I will need to use another program to manipulate the object prior to plot due to its size. I have the following tools available:
VB6
Autocad
(Do not have Adobe Writer)
Is there a way to get this print object to Autocad or even as a bitmap?
Thanks is advance,
bds
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Nov 12, 2007
What is the iso sql query to get the relationships between all tables in a db?
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Aug 3, 2006
I have spend days researching this and found others with the exact same
problem but there are no useful replies as people don't seem to
understand our problem. Please read this carefully...
What is the best way to create relationships between new SQL tables? For example, say I want to create a new database with tables for Customer, Orders and Details, how to I relate these tables?
- Edit via the Dataset designer in Visual Studio 2005?
- Use the Server Explorer's Table designer in Visual Studio? (not sure how to use the 'relationship' icon)
- Use SQL Server Managment Studio Express (SSMSE) Database Diagram
- Something else?
I am using Visual Studio 2005 Standard and SQL Server 2005 Express (SP1).
I created a new database in Visual Studio's Server Explorer and then used the Table Designer to create two new Tables (Customers and Orders). I then assigned primary keys but I don't know the best way to relate the tables.
If I create and edit a new dataset, I can graphically drag a relationship between the tables. HOWEVER, this relationship isn't recognized by SQL Server Management Studio Express (SSMSE). I found this out when I tried to create a database diagram, none of the relationships appear in SQL?! This would cause problems when I want to deploy the database to my client.
If however, I START in SSMSE and create the tables there, then open a Database Diagram in SSMSE and graphically link the tables, then Visual Studio will see all the relationships.
I thought it was supposed to be a seamless integration between Visual Studio 2005 and SQL Server 2005. Am I missing something?
Richard
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Mar 29, 2008
Can I programatically access all relationships for a sql table? I know i can do this in the table designer ...
---Jim
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May 30, 2008
:eek: =>First ,2nd ,3rd normalization
=>Data Integrity
=>Mappings-
1 1:1 mappings
2 1:2 mappings
3 Many :MAny mappings
=>Establish relationship
1.Simple
2.Complex
3. Multiple
Defination of these all or details with subjects also
pls reply me soon
it is urgent for me
thanks in advance
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Jul 23, 2005
What is the best way to setup relationships between one lookup tableand many other tables. The tables did not have any lookup tablerelationships which I am adding. One lookup table is used for same datain several different places.To use one lookup tables with several tables, I had to disable "CascadeUpdate" and only have "enforce relationships for updates and inserts"checked.Any pros/cons?Thanks in advance.P
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Nov 9, 2005
Hello,I want to be able to view data from 3 tables using the JOIN statement, butI'm not sure of how to do it. I think i don't know the syntax of the joins.Iimagine this is easy for the experienced - but Im not.Allow me to explain:I have 2 Tables: PERSON and SIGNPERSON------PersonNo int (Primary Key)Name varchar(50)StarSign intFavFood intSIGN----StarSign int (Primary Key)StarSignName varchar(50)Relationship: SIGN has a one-to-many relationship with PERSON. The linkingfield is called 'StarSign'.Question 1:I want to display all the peoples names, and their star sign (whether theyhave one or not).Answer 1:SELECT PERSON.Name, SIGN.StarSignNameFROM PERSON LEFT OUTER JOIN SIGN ON PERSON.StarSign = SIGN.StarSign;No problems there. But now I want to do the same thing, but have theirfavourite food displayed as well. So an additional table is needed:FOOD----FavFood int (Primary Key)FavFoodName varchar(50)Relationship: FOOD has a one-to-many relationship with PERSON. The linkingfield is called 'FavFood'.Question 2:I want to display all the peoples names, their star signs (whether theyhave one or not), and their favourite food (whether they have one or not).Answer 1:???I'm not sure what to do. Notice that I want to use an LEFT OUTER JOIN so ALLthe rows from table PERSON will appear 'irrespective' of whether they haverelated records in the other tables.Jack.
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Mar 26, 2008
I'm building an application that tracks courses and equivalent courses. For example, say I have course A which a user should get credit for if they have taken equivalent courses. So if a user has taken (course B or course C) AND (course D or course E) he should get credit for Course A. What's the best way to setup a SQL table to create these type of equivalent relationships?
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Aug 22, 2007
Hi,
I'm looking for a query I can use to alter table relationships. What I want to do in particular, is to set every relationship to cascade on update. Can anyone point me out to a solution? MSDN seems very vague in this subject.
Thanks,
Tiago
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May 5, 2015
I'm using Sql Server 2012 Enterprise and have a database with over 400 tables. I am looking at one diagram which contains about 20 (or so) tables and their relationships. When I right-click on a relationship line I only see information about which tables are connected on that line but not on which fields. Can I get that information from the Diagram or can I only get that from the sys tables?
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Jan 18, 2008
I'm designing a database with 3 tables called Function, Test andScene.A Function has multiple Tests, but a Test has only one Function. Amany to many relationship exists between Test and Scene therefore Ineed a junction table between these two tables - giving 4 tables intotal. The Test table would store a foreign key, the primary key ofthe Function table.There is a problem with design though and that is that Functions andScenes are actually defined before the Test is defined. Therefore itshould be possible to create a Function and add to id its Scenes,before Tests have been defined. In other words, Scenes are as much apart of a Function as they are of Tests. Tests are in fact only ofrelavence to testers. Anyway, to satisfy this scenario, a Junction boxis also needed beween Function and Scene. This creates a loop betweenall tables.Is this a good approach? Any other suggestions or advice on thematter? Any advice regarding data integrity?Thanks,Barry
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Apr 11, 2006
Hello again,
I'm going through my tables and rewriting them so that I can create relationship-based constraints and create foreign keys among my tables. I didn't have a problem with a few of the tables but I seem to have come across a slightly confusing hiccup.
Here's the query for my Classes table:
Code:
CREATE TABLE Classes
(
class_id
INT
IDENTITY
PRIMARY KEY
NOT NULL,
teacher_id
INT
NOT NULL,
class_title
VARCHAR(50)
NOT NULL,
class_grade
SMALLINT
NOT NULL
DEFAULT 6,
class_tardies
SMALLINT
NOT NULL
DEFAULT 0,
class_absences
SMALLINT
NOT NULL
DEFAULT 0,
CONSTRAINT Teacher_instructs_ClassFKIndex1 FOREIGN KEY (teacher_id)
REFERENCES Users (user_id)
)
This statement runs without problems and I Create the relationship with my Users table just fine, having renamed it to teacher_id. I have a 1:n relationship between users and tables AND an n:m relationship because a user can be a student or a teacher, the difference is one field, user_type, which denotes what type of user a person is. In any case, the relationship that's 1:n from users to classes is that of the teacher instructing the class. The problem exists when I run my query for the intermediary table between the class and the gradebook:
Code:
CREATE TABLE Classes_have_Grades
(
class_id
INT
PRIMARY KEY
NOT NULL,
teacher_id
INT
NOT NULL,
grade_id
INT
NOT NULL,
CONSTRAINT Grades_for_ClassesFKIndex1 FOREIGN KEY (grade_id)
REFERENCES Grades (grade_id),
CONSTRAINT Classes_have_gradesFKIndex2 FOREIGN KEY (class_id, teacher_id)
REFERENCES Classes (class_id, teacher_id)
)
Query Analyzer spits out: Quote: Originally Posted by Query Analyzer There are no primary or candidate keys in the referenced table 'Classes' that match the referencing column list in the foreign key 'Classes_have_gradesFKIndex2'. Now, I know in SQL Server 2000 you can only have one primary key. Does that mean I can have a multi-columned Primary key (which is in fact what I would like) or does that mean that just one field can be a primary key and that a table can have only the one primary key?
In addition, what is a "candidate" key? Will making the other fields "Candidate" keys solve my problem?
Thank you for your assistance.
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May 29, 2007
Ok, so I open up a book on beginning sql and it discusses relationships.There is something that appears wrong. I am not understanding how the book is describing the one to one relationship. In it's figure, it shows that the same agency can have two different artist id's. But according to it's definition of one to one list can be related from both tables.Can someone explain this further please?Thanks in advance.
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Aug 8, 2007
How do you show many to many relationships in ASP.NET with datasources?
I can retrieve the information from the database easily but I can't manage to save that information into a variable so that i can then call for only information in the M2M table related to the ID Key I want. For example..1 <asp:Label ID="lblTestLabel" Text='<%# DataBinder.Eval(Container.DataItem, "title_id") %>' Runat="server" />
2
3 <script language="VB" runat="server">
4 sub Page_Load(sender as Object, e as EventArgs)
5 Dim lblTitleID As Label = Repeater1.FindControl("lblTestLabel")
6 Response.Write(lblTitleID.text)
7 End Sub
8 </script>
When I try to run this script it dosn't work and I get the error:
System.NullReferenceException: Object reference not set to an instance of an object.
For line 6 of the code above. Is there a way to just retrieve information from a datasource without storing information into a label first?
PS: I use sqldatasource tags to retrieve information like:1 <asp:SqlDataSource ID="DataSet1" runat="server"
2 ConnectionString="Driver={MySQL ODBC 3.51 Driver};server=localhost;database=;user=;pwd=;option=3;"
3 ProviderName="System.Data.Odbc"
4 SelectCommand="Select * from titles order by title_id">
5 </asp:SqlDataSource>
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Aug 10, 2007
Can someone help me sort something out. Suppose we have two tables in a database.One is named Person, and one is named Birthday. Is this a many to many relationshipor a 1 to many relationship?
Person has many birthdays. Example. Joe Schmoe has a birthday for every year of his life. birthday(7/11/1976) has many People (Many people have a birthday on 7/11/1976.
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Feb 2, 2004
Is there any easy way of getting all the relationships for the tables in aSQL server db? I've looked through Google and the Books online but I'm barely scratching the surface on the systables. I know I can go to each individual table and get the dependencies or even print out the diagram through Enterprise Manager but I really don't want to have to type out all the primary/foreign keys for 100+ tables. Any help on getting this data either through a 3rd party software or querying the systables would be great.
THT
DMW
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Mar 21, 2001
We have a table with approximately 150 colums and 2/3 of them are bit datatypes. We do not expect much activity on this table. Does it make sense to separate it into a few tables instead of 1 with one-to-one relationships? Will the join(s) significantly slow down our web application? Thank you
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Aug 6, 2004
My hosting servers have "myLittleAdmin" installed. I am new to ms sql I have some experience with Access but I have never set up Relationships inside the database server. I have always just relied on my application logic to call the relations. What is the benefit to setting up relationships in sql, if any?
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