ALTER TABLE [Students] WITH CHECK ADD CONSTRAINT [FK_Students_Schools]
FOREIGN KEY([SchoolId]) REFERENCES [Schools] ([SchoolId])
What kind of index would ensure best performance for INSERTs/UPDATEs, so that SQL Server can most efficiently check the FK constraints? Would it be simply:
CREATE INDEX IX_Students_SchlId ON Students (SchoolId)
Or
CREATE INDEX IX_Students_SchlId ON Students (SchoolId, StudentId)
In other words, what's best practice for adding an index which best supports a Foreign Key constraint?
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,
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,
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?
I'm shredding the below xml into relational tables. Each element of the xml has it's own table and there is a foreign key to join the tables, you can see this in the below picture. The process I follow is each relational table I always bring the nesecary xml and store it in the table and when shredding I always look at the parent table.So for example when processing the seat table, I use seat xml from the parent route table, also taking the ROUTEID from the route table. The reason I do this is all about taking the id from the previous step to create the relationships between the tables. without taking the xml down to the tables?The problem with this approach is I have xml stored in most tables and the tables are becoming very large.
I use the following 3 sets of sql code in SQL Server Management Studio Express (SSMSE) to import the csv data/files to 3 dbo.Tables via CREATE TABLE & BUKL INSERT operations:
-- ImportCSVprojects.sql --
USE ChemDatabase
GO
CREATE TABLE Projects
(
ProjectID int,
ProjectName nvarchar(25),
LabName nvarchar(25)
);
BULK INSERT dbo.Projects
FROM 'c:myfileProjects.csv'
WITH
(
FIELDTERMINATOR = ',',
ROWTERMINATOR = ''
)
GO ======================================= -- ImportCSVsamples.sql --
USE ChemDatabase
GO
CREATE TABLE Samples
(
SampleID int,
SampleName nvarchar(25),
Matrix nvarchar(25),
SampleType nvarchar(25),
ChemGroup nvarchar(25),
ProjectID int
);
BULK INSERT dbo.Samples
FROM 'c:myfileSamples.csv'
WITH
(
FIELDTERMINATOR = ',',
ROWTERMINATOR = ''
)
GO ========================================= -- ImportCSVtestResult.sql --
USE ChemDatabase
GO
CREATE TABLE TestResults
(
AnalyteID int,
AnalyteName nvarchar(25),
Result decimal(9,3),
UnitForConc nvarchar(25),
SampleID int
);
BULK INSERT dbo.TestResults
FROM 'c:myfileLabTests.csv'
WITH
(
FIELDTERMINATOR = ',',
ROWTERMINATOR = ''
)
GO
======================================== The 3 csv files were successfully imported into the ChemDatabase of my SSMSE.
2 questions to ask: (1) How can I designate the Primary and Foreign Keys to these 3 dbo Tables? Should I do this "designate" thing after the 3 dbo Tables are done or during the "Importing" period? (2) How can I set up the relationships among these 3 dbo Tables?
How can i enter Default Values of " " to all the columns of type characterof all the tables (excluding system tables) and Default Values of 0of all columns of type numbers. Excluding all primary key columns.Thank you
If i create a simple table with a foreign key constraint, does itcreate an implicit index on that given ID? I've been told this isdone in some databases, but i need to know for sure if SQL Server doesit. Has anyone heard of this before, on any other databses perhaps?Heres an example of how the foreign key constraint is being added:ALTER TABLE [dbo].[administrators] WITH CHECK ADD CONSTRAINT[FPSLUFSUOXZGAJOJ] FOREIGN KEY([AdministratorRoleID])REFERENCES [dbo].[administratorroles] ([AdministratorRoleID])My initial testing seems to indicate adding an index on the foreignkey column helps, but i need to know for sure. Any insight would begreatly appreciated!Bob
I have an application in which i need to get the foreign key fieldsfrom a table and then get all the foreign keys primary key field fromthe linking table. Could some one tell me how i do this usingINFORMATION_SCHEMA. I have tried and can get the foreign keys but notsure how to get the associated primary keys.
I have a 3rd party app which had a primary key with about 5 fields. The last field of this was a trantype. This app had a posting process which uses this in it's sql. Ran rather slow. We added an individual index to this field and cut processing down 90%. It almost seemded like sl server was ignoring this index. Is this because it was the last field in the primary key index?
I have recently been looking at a database and wondered if anyone can tell me what the advantages are supporting a unique collumn, which can essentially be seen as the primary key, with an identity seed integer primary key.
For example:
id [unique integer auto incremented primary key - not null], ClientCode [unique index varchar - not null], name [varchar null], surname [varchar null]
isn't it just better to use ClientCode as the primary key straight of because when one references the above table, it can be done easier with the ClientCode since you dont have to do a lookup on the ClientCode everytime.
I am having trouble dropping constraints(Primary and Foreign Keys). I would like to do so so I can truncate the tables and repopulate them. Any time I use the DROP CONSTRAINT #### on one table, I get an error message saying this is referenced in another table. Any help in how to drop the keys so I can truncate the tables in a database would be appreciated. I must be overlooking something simple. Thanks for the help.
Be warned, index padding is not included in this, and I'm not sure the fillfactor setting is correct.
set nocount on create table #PK(constraint_schema sysname not null, constraint_name sysname not null, sql varchar(4000) not null, constraint PK_#PK primary key clustered(constraint_schema, constraint_name)) create table #cols(constraint_schema sysname not null, constraint_name sysname not null, column_name sysname not null, ordinal_position int not null, constraint PK_#PKcol primary key clustered(constraint_schema, constraint_name, ordinal_position)) create table #FK(constraint_schema sysname not null, constraint_name sysname not null, unique_constraint_schema sysname not null, unique_constraint_name sysname not null, sql varchar(4000) not null, constraint PK_#FK primary key clustered(constraint_schema, constraint_name))
insert into #PK select constraint_schema, constraint_name, 'ALTER TABLE ' + quotename(table_schema) + '.' + quotename(TABLE_NAME) + ' ADD CONSTRAINT ' + quotename(CONSTRAINT_NAME) + ' PRIMARY KEY ' + CASE WHEN si.indid<>1 THEN 'NON' ELSE '' END + 'CLUSTERED (>cols<) WITH FILLFACTOR=' + cast(si.OrigFillFactor as varchar) + ' ON ' + quotename(fg.groupname) AS SQL from INFORMATION_SCHEMA.TABLE_CONSTRAINTS TC INNER JOIN sysindexes si on TC.CONSTRAINT_NAME=si.name inner join sysfilegroups fg on si.groupid=fg.groupid WHERE CONSTRAINT_TYPE IN('PRIMARY KEY','UNIQUE')
insert into #fk select c.constraint_schema, c.constraint_name, c.unique_constraint_schema, c.unique_constraint_name, 'ALTER TABLE ' + quotename(F.table_schema) + '.' + quotename(F.table_name) + ' ADD CONSTRAINT ' + quotename(F.constraint_name) + ' FOREIGN KEY(>cols<) REFERENCES ' + quotename(r.table_schema) + '.' + quotename(r.table_name) + '(>rcols<)' AS sql FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS F INNER JOIN INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS C ON F.constraint_schema=C.constraint_schema AND f.constraint_name=c.constraint_name AND F.constraint_type='FOREIGN KEY' INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS R ON R.constraint_schema=C.unique_constraint_schema AND r.constraint_name=c.unique_constraint_name AND r.constraint_type in ('PRIMARY KEY','UNIQUE') ORDER BY F.table_name, r.table_name
insert into #cols select constraint_schema, constraint_name, COLUMN_NAME, ORDINAL_POSITION from INFORMATION_SCHEMA.KEY_COLUMN_USAGE
update P SET SQL=Replace(SQL, '>cols<', @delim + quotename(c.column_name) + '>cols<') FROM #PK P INNER JOIN #cols C ON P.constraint_schema=C.constraint_schema AND P.constraint_name=C.constraint_name WHERE C.ORDINAL_POSITION=@ctr
UPDATE F SET SQL=Replace(Replace(SQL, '>cols<', @delim + quotename(c.column_name) + '>cols<'), '>rcols<', @delim + quotename(r.column_name) + '>rcols<') FROM #FK F INNER JOIN #cols C ON F.constraint_schema=C.constraint_schema AND F.constraint_name=C.constraint_name AND C.ordinal_position=@ctr INNER JOIN #cols R ON F.unique_constraint_schema=R.constraint_schema AND F.unique_constraint_name=R.constraint_name AND C.ordinal_position=R.ordinal_position
select @ctr=@ctr+1, @delim=',' END set nocount on
update #PK SET SQL=Replace(SQL, '>cols<', '') update #FK SET SQL=Replace(Replace(SQL, '>cols<', ''), '>rcols<', '')
All of the 3 books I've read say it is not a good idea to create a clustered index on the primary key but it is created as the default. My question is has this changed in 2005? My understanding is to create the clustered index on columns used first in join clauses and then in where clauses, what is the answer?
I'm just getting my feet wet with how encryption works in SQL 2005. With regards to the encryption of primary / foreign keys, I'm not entirely clear on the best approach. Below are three examples of typical table structures I currently have:
The Customers and Orders tables use identity values as their primary keys. From what I can tell, CustomerID in the Customers table cannot be encrypted and OrderID in the Orders table cannot be encrypted because they are identity values. In these cases, would it be safer (in terms of security) to create a separate, meaningless identity key column in the Customers table and then remove the identity attribute from CustomerID so I can encrypt CustomerID?
Similarily in the OrderDetails table, OrderID and ItemNumber form a composite key. These values are important in that I don't want them to be tampered with. Am I better off creating a separate identity key column which becomes the table's primary key ... then encrypt both the OrderID and ItemNumber columns in this table?
I have a deal table, each of these investments must be unique. I created a int pk : idDeal. Does that make sense or should i just use the deal colm being it has a unique constraint, Reguarding indexes, should i make the auto # colm my pk and make that the clustered index? and put another index on the Deal Colmn? Any suggestions welcomed
Ok, so I've broken down and decided to write myself an invoicing program. I'd like to use GUID fields as the Primary Keys in my table. Now, I basicly bill for two seperate items:
Deliverables and Services.
So, my Layout's gonna look something like
Create Table Invoice( ID UniqueIdentifier Primary Key, -- Other Data );
Create Deliverable( ID uniqueidentifier Primary Key, ParentInvoice uniqueidentifier, -- Other data); --...
Im sure there are probems with that as it's written feel free to edify me as to what they are.
my questions are such:
1) Does a uniqueidentifier field automagically get a value? 2) If not how do I generate one in TSQL? 3) If so, what do I use to store my Foreign Keys. 4) How do I declare my Foreign key constraints?
I've attempted to identify a primary and foreign key in these two tables, but I am getting a bunch of errors re duplicate keys and column names needing to be unique.Perhaps the primary and foreign key I have identified don't meet the criteria?
CREATE TABLE StockNames ( -- Added Primary key to [stock_symbol] [stock_symbol] VARCHAR(5) NOT NULL CONSTRAINT PK_stock_symbol PRIMARY KEY, [stock_name] VARCHAR(150) NOT NULL, [stock_exchange] VARCHAR(50) NOT NULL,
Hello!I have a table A with fields id,startdate and other fields. id and startdateare in the primary key.In the table B I want to introduce a Foreign key to field id of table A.Is this possible? If yes, which kind of key I have to build in table A?Thx in advance,Fritz
Pls let me know How I generate script for All primary keys and foreign keys in a table. Thereafter that can be used to add primary keys and foreign keys in another databse with same structure.
Also how I script default and other constraints of a table?
I wanted to find all occurrences of ADRSCODE in a Database where ADRSCODE is in either an Index or a Primary Key.
I know how to get all of the occurences of ADRSCODE in a database and the table associated with it, I just want to tack on the Index and/or primary key.
hi. How to update FormA table from customer table. Let say i wish to keep small number of fields from each table so i use foreign keys as reference. However i had a problem when i tried to save the relationships of both tables, i receive the error that FormA_id is not able to insert null into value. Cust_id(PK) is identify column, as well FormA_id(FK) and FormA_id(PK) too. For example, when i insert a record from customer table, it will automatically create id for FormA. Table structure. Customer cust_id(PK),name,age,formA_id(FK) Table structure, FormA formA_id(PK), info, date, How to solve ?
I have a table called Appointment, for storing (you guessed it) appointments at a medical practice. If an appointment is cancelled, I want to collect a cancellation reason, so let's say that I create a second table called Cancellation which has a foreign key relating to the Appointment table's primary key, AppointmentID, and another column, Reason. Now, in order to indicate that an appointment was cancelled, I could include a Cancelled column in the Appointment table with a bit datatype, or instead I could infer that an appointment must be cancelled if it has a corresponding record in the Cancellation table.
It may be that it'd be better to store the cancellation reason in the Appointment table - But regardless, let's say I stick with the two-table solution described above, and I subsequently want to write a query to list all appointments which have been cancelled. If I had the Cancelled column in the Appointment table, I could simply query for all records in that table where that column's value was FALSE. If I went the other way and DIDN'T have a Cancelled column, I could instead write a query joining the Appointment and Cancellation tables to return all records in Appointment with a corresponding record in Cancellation.
That latter method, whilst slightly more complicated because it involves joining two tables, seems to me to be the most normalised. Instead of storing the fact that an appointment is cancelled in two different tables, that fact is only stored in the Cancellation table. Would there be a performance hit in using the two-table, 'inferred cancellation' method rather than just having a bit column in the Appointment table? Would that performance hit be enough to persuade you to use a Cancellation column in the Appointment table instead? And what about if I were to apply that method to other things associated with each appointment, e.g. Is it completed? Is it chargeable to the client or an insurance company? Is the client and in-patient or out-patient?
We have a database with hundreds of tables, each with "CreatedByLoginId" and "ModifiedByLoginId" FK columns back to the Login table. This is all fine and well, but 500+ tables all link back to Login table every time a record is inserted or updated.
For strictly performance reasons, what do you think of us REMOVING the FK constraints on all of our tables? While this does mean that a GUID that is not a valid LoginId could potentially be put in a table, I'm not too worried about it because users don't have direct access to the database.
I have a setup with a bridge table. There are about 5 different tables on one side of the bridge (all with compatable PK columns) one of which is called 'mobilesub', and one on the other side called 'allcostcenters'. The bridge table is called 'subaccountcostcenter'.
I can enter data for mobilesub in the bridge table. But then when I try to enter the info into the bridge table for any of the other tables, such as localsub, there is a conflict like this:
INSERT statement conflicted with TABLE FOREIGN KEY constraint 'FK_subaccountcostcenter_mobilesub'. The conflict occurred in database 'test1', table 'mobilesub'. The statement has been terminated.
Is there some rule against using a bridge table that references several different tables, and I'm just not aware of it. Because I've done everything I can to make sure the info from the different tables don't conflict . . . The same error comes up if I do the localsub table first--in that case the foriegn key messing me up is FK_subaccountcostcenter_localsub. So it's not something with the individual tables.
I know altering the schema of system tables is a big no-no, but I was wondering if setting up a table that has foreign keys pointing to a system table is bad.
Basically what I'm refering to is in some cases I have CreationDate and CreatedBy fields in my tables that correspond to GETDATE() and USER_NAME() functions in insert statements....I want the CreatedBy field to be a valid SQL server DB username ... and not some unchecked string value (SYSNAME actually)
I am trying to execute following sql script in sql-server 2000 query analyzer
CREATE TABLE user_courses (user_id varchar(30) NOT NULL PRIMARY KEY, course_id varchar(10) NOT NULL PRIMARY KEY)
Its give's me following error :- Cannot specify multiple primary key constraint
Hence I am not able to ceate table with multiple primary keys. So can any one tell me how to get this done?.
Secondly, Primary key must be unique i.e duplicate values are not allowed in P.K field. But in this case since I am declaring two fileds as primary keys. Will it allow me to have following records in the user_courses table? user_id(P.K) course_id(P.K) bob CRS235 alice CRS235 Tim CRS235 tom CRS635
So, if we consider both the fields as primary keys together than I am not voilating Uniqueness constraint. But, if I look at course_id alone then I am voilating uniqeness property?
I have a situation that I must resolve. I have a program being used by many but I had to create a new table to provide a new feature. The problem I have is this table must use the primary key from the parent table as its primary key, meaning when a user adds a new record to parent table, I need to instantly add the primary key to the child table. Now this was done in the program using sql statements, but I need to implement a trigger or such as to keep me from having to reinstall application on many computers.
basically person inserts new record, then I need to get the new primary ket and add insert it into the child tables. how can I do this with a trigger. I have tried to use an insert into statment with my trigger, but I can't seem to pass the parameters correctly.
CREATE Trigger dbo.Table_Borrower_Insert_Keys ON Table_Borrower AFTER INSERT AS begin declare @bid as int
@bid = select MAX(BorrowerID) FROM Table_SoldProgression
INSERT Table_SoldProgression(BorrowerID) values (@bid) end GO
another attempt
CREATE Trigger dbo.Table_Borrower_Insert_Keys ON Table_Borrower AFTER INSERT AS
Does anyone have a script that will roll through the tables in a database and identify tables without primary keys defined? I did not see any in the online script database.
Hello,We imported a bunch of tables from a database and realized that theprimary keys weren't copied to the destination db. In order to re-create the keys, we need to know which tables have them. Is there acommand that I can use (on the source db) to find out which tablescontain primary keys? The db has hundreds of tables and I'd rather notgo through each one to see which has a primary key.Also, for future reference, is there a way to include the primary keyon an import?Thanks,Peps
I've created a table called Employees with a primary key called EmployeeID. The table contains EmployeeID, FirstName and LastName columns. I now want to create a table called Team which will contain the columns TeamID, EmployeeID (to reference the column EmployeeID from the Employee table) and a column called TeamName. Sql won't let me create multiple primary keys in one table (I did think that was the case ) key but yet if I look at the Adventure Works database in the Person.PersonPhone table, I can see three primary keys defined.
