I am currently undertaking a review of the primary keys in a SQL Server
2000 database with a view to improving performance of queries.
I have heard that, in the case of compound primary keys, it is
important to select the correct order for the columns within the key.
For instance, imagine a table called OrderLine which has primary key
columns as follows-
Ledger
OrderNumber
OrderLineNumber
The theory I have heard is that columns with the most distinct values
should come first. In this case, Ledger is likely to have a maximum of
6 distinct values, OrderNumber a maximum of 10 million and OrderLine up
to 99. Based on this supposition I believe the best order would be-
OrderNumber
OrderLineNumber
Ledger
I have performed a few rudimentary tests that appear to bear this out.
I was wondering if anyone else has tried something similar and if so
what was the result?
Hi all, In my project i will have the data in a collection of objects, I need to update series of tables with foreign key relations Right now my code looks like this foreach(object obj in Objects){ int accountId=Account.Insert(obj.accountOpenDate,obj.accountName);//this will update the accounts table and returns account id which is a Identity column in Acccounts table int DebtId=Debt.Insert(accountd,obj.debtamount,obj.debtbalance); this will update the Debts table and returns DebtId ///series of tables like above but all the relevant data comes from obj and in the Insert Methods i am using stored procedures to Insert the data into table } The no of objects varies from 1000 to 1 milliion,, with this approach its taking more time to update all the data. Please let me know if any alternative procedure to handle this kind of scenario.
I am designing a database. I want to define a automatic sequence on a table primary key field. what is the best solution for it?
I know I can enable identity property for a field, but it has some problems ( for example its seed jumps on restart and unsuccessful events)
I also can use some calculated sequences. for example I can calculate max of the filed values and after incrementing use it as key for new inserted record.
Hello,I am learning SQL Server and I would like to ask you a question. Couldyou tell me please if sequence of columns in a table has influence onperformance?Thank you very much/RAM/
Table BSadIt contains the same fields as in table A and will have sequence number in which the concatenation should happen. The length field(LEN) will have corresponding field lengths(pipe delimited) should be considered in concatenation)
Note: If the field length given in Table B doesn't match with actual size of the fields then, the field should be filled with 2 left spaces while concatenation.. Eg. In above example say LIFNR value = 88390234(len =icon_cool.gif
then after concat the value should be like below:
12345678904355325363a234 88390234
Note:The fields are not constant..I have around 40 fields like that in which any combination of fields can be possible...eg..
I am not sure which field has the value 1, 2 etc.. and how many fields are forming the combination..It can be sometimes 3/40 fields or it can be 10/40 fields...I have to dynamically get those values and concat...
I can have any number of fields for concatenation..above example is just for 4...it should be dynamic enough to handle any number of fields..
I have a table which has two column like following table and I don't know how can I update theses two column with identity numbers but just the fields which are equal 111.
I have a requirement where in I have to concatenate the fields based on their sequence given in another table along with respect to their lengths. eg..
Input 1:
Table A: (below are the fields and their respective values, not all fields will have values) ----------- KSCHL - ZIC0 (KEY) KOTABNR - 521 (KEY) MATNR KUNNR-->1234567890 LIFNR VKORG-->a234 PRCTR KUNRE-->4355325363 LIFRE-->88390234 PRODH
Table BIt contains the same fields as in table A and will have sequence number in which the concatenation should happen. The length field(LEN) will have corresponding field lengths(pipe delimited) should be considered in concatenation)
Note: If the field length given in Table B doesn't match with actual size of the fields then, the field should be filled with 2 left spaces while concatenation.. Eg. In above example say LIFNR value = 88390234(len =icon_cool.gif then after concat the value should be like below:
12345678904355325363a234 88390234
Note:The fields are not constant..I have around 40 fields like that in which any combination of fields can be possible...eg..
I am not sure which field has the value 1, 2 etc.. and how many fields are forming the combination..It can be sometimes 3/40 fields or it can be 10/40 fields...I have to dynamically get those values and concat...
I can have any number of fields for concatenation..above example is just for 4...it should be dynamic enough to handle any number of fields..
I have a question in SQL server. For example I have a table which has two column like following table and I don't know how can I update theses two column with identity numbers but just the fields which are equal 111.
Hi Guys, When I create a table with a composit primary key with 18columns. I get this error "Cannot specify more than 16 column names for index key list. 17 specified." I really have to have these columns as primary key. Is there any workaround to create this table; Thanks
How can I create a primary key on two columns? I could not find any sensible code sample or description how it should be done. It is clear from MSDN that it is possible but there are no examples.
There is a textbox "Included Columns" in one of the tools for setting primary keys for one column but it does not allow me to enter anything.
Hello all. I need to extract the column names that form the primary key group on a table in SQL Server. I have a table called Account and it contains ten columns. The primary key consists of two columns - MasterAccountID, AccountID. This primary key is a unique constraint and is clustered (it acts as an index as well as a primary key group). I have tried the following to no avail:exec sp_pkeys Account -> returns no rowsexec sp_helpindex Account -> throws an error stating that the object 'Account' does not existIf I run the following SQL statement, I can see all of the PK_* constraints in the database, so I know they are there:select * from information_schema.table_constraintswhere constraInt_type IN ('PRIMARY KEY','FOREIGN KEY') Again, I need to be able to specify a table name and have it return the columns (don't care if it returns extra fields) that make up the primary key fields for that table. Thanks!
I want to get the Primary Key Columns in Arrays by sending a tablename. I am using SQL Server 2000 and I want to make a find utility in VB.net whichwill work for all the forms; I have tables with one Primary key and some tables with composite Primary keys. I used to do this in VB 6 by making a function which fills the Primary Keys inList Box (I require to fill in list box), now I need to get in array. Can some one tell me the migration of the following VB 6 Code? This was written for the MS Access, I need same for SQL Server, I cannot find Table Def and Index Object in VB.net 2003. Public Sub GetFieldsFromDatabase (ldbDatabase As Database, lsTableName AsString) Dim lttabDef As TableDef Dim liCounter As Integer Dim liLoop As Integer Dim idxLoop As Index Dim fldLoop As Field With ldbDatabase For Each lttabDef In .TableDefs If lttabDef.Name = lsTableName Then liCounter = lttabDef.Fields.Count For liLoop = 0 To liCounter - 1 cboFieldLists.List(liLoop) = lttabDef.Fields(liLoop).Name Next liLoop For Each idxLoop In lttabDef.Indexes With idxLoop lblIndexName = .Name If .Primary Then liCounter = 0 For Each fldLoop In .Fields cboPrimaryKeys.List(liCounter) = fldLoop.Name liCounter = liCounter + 1 Next fldLoop End If End With Next cboFieldLists.ListIndex = 0 If cboPrimaryKeys.ListCount > 0 Then cboPrimaryKeys.ListIndex = 0 End If Exit For End If Next End WithEnd Sub
Hi , Plz help me. The scenario is as follows I have a db on sql server 2005.I have replicated the db on sql server 2000.All the data counts seems to be correct.But the online websites are not able to execute queries generating error(Microsoft OLE DB Provider for sql server error '80040e21'.Multiple step OLE DB operation generated errors.Check each OLE DB status value,if available.No work was done.)Same web aspcode is working for other db (which were replicated from sql server 2000). Also one more thing that was observed is as follows: 1)Prmary key was replicated for some of the tables.When primary keys were removed manually report executed fine.
Can a Primary Key column also be a Identity column? The reason I am asking this question is because I have created a table and each time I insert data into the Address Table I am also inserting the AddressID, how do I get the Primary Key (AddressID column) to self generate ID values.
I've two tables A, B. In A table, I need to define the primary key with combination of 2 columns and this Primary Key will be a foreign key in table B. Based on these PK and FK I'll be writing a join to get the second column in table B.
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
I frequently have the problem where I have a list of items to delete ina temp table, such asProjectId Description------------- ----------------1 test12 test43 test34 test2And I want to delete all those items from another table.. What is thebest way to do that? If I use two IN clauses it will do it where itmatches anything in both, not the exact combination of the two. I can'tdo joins in a delete clause like an update, so how is this typicallyhandled?The only way I can see so far to get around it is to concatenate thecolumns like CAST(ProjectId as varchar) + '-' + Description and do anIN clause on that which is pretty nasty.Any better way?
In my current database design, there is one table (PState) which has a Primary Key (int) and a few other fields.
During development, a pattern started to arise; for certain rows in PState, I wanted to specify an additional set of columns (over 10 of them with quite large lengths) for each row in PState. However, as these additional columns would only be required in approximately 20% of the rows of PState, there would be plenty of NULL values in PState if I would make this table wider than necessary. So, I decided to create a separate table with those optional columns (PStateWFI). In order to attach these additional columns in PStateWFI to PState in the cases they were needed, I would obviously have to create a Foreign Key constraint on the Primary Key of PStateWFI so that these optional rows would know which row in PState they would belong to.
However, the problem with this approach is that one could define multiple rows in PStateWFI referring to the same row in PState, which would not make sense. Thus, a UNIQUE index constraint added to the constrained ID column in PStateWFI would make sense to ensure that there could only be one set of optional columns added to each row in PState. But now, when adding the UNIQUE index, the FK constraint started to appear as a bidirectional key link in the Diagram; hence, new entries in PState would have to meet a FK constraint based on PStateWFI, which was not intended.
Hence, I had to create a quite awkward design to enforce the constraints:
1. The PState table has a Primary Key (PState.ParticleID, int, Identity Specification: Yes) 2. The PStateWFI table has a Primary Key (PstateWFIID, int, Identity Specification: Yes) 3. PStateWFI has field "PStateID" which has a FK constraint to PState.ParticleID (which is a one-way constraint operating in the correct way and does not constrain insertions in PState) 4. PStateWFI has an additional column ParticleIDIndex which has a UNIQUE Index attached to it. 5. There is a check constraint on PStateWFI enforcing PStateWFI.ParticleIDIndex = PStateWFI.ParticleID.
Although this structure does the job, it makes it necessary to add a redundant column in PStateWFI by duplicating the PStateWFI.ParticleID into PStateWFI.ParticleIDIndex, since I can't create a UNIQUE index on PStateWFI.ParticleID without constraining the PState table as well. So, insertions into this table would have to insert the same value into two columns. Not a big deal, but appears slightly ugly.
Basically I'd hope someone could explain why a bidirectional FK constraint has to be enforced on the primary key table in a relationship when the constrained column in the primary key table has a UNIQUE index attached on it. I have a few other cases where the above approach would benefit from a more clear structure.
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?
Case: Exporting Report to PDF/Printing/TIFF Report: Contains 1 table with 19 Columns. 1 column is static, the other 18 are visible at the users descretion. Report when printed/exported to pdf spans 2 pages naturally, 16 on the first page, 3 on the second, and the column widths have been adjusted to provide a perfect page span .
User A elects to hide two of the columns, and show the rest. The report complies and the viewable version is perfect, the excel export is perfect.. the PDF export on the first page causes every fith column, starting with the last column that was hidden to be expanded to take up additional width. On the spanned page, it renders the first column on that page correctly, then there is a white space gap equal to the width of the hidden columns and then the rest of the cells show with the last column expanded to take up the same width that the original 2 columns were going to take up, plus its width.
We have tried several different settings to see if it helps this issue or makes it worse. So far cangrow/canshrink/keep together have made no impact. It is not possible to increase the page size due to limited page size selection availablility for the client. There are far too many combinations of what the user can elect to show or hide to put together different tables to show and hide on the same report to remove this effect.
Any help or suggestion on this issue would be appreciated
Uma writes "Hi Dear, I have A Table , Which Primary key consists of 6 columns. total Number of Columns in the table are 16. Now i Want to Convert my Composite Primary key into simple primary key.there are already 2200 records in the table and no referential integrity (foriegn key ) exist.
may i convert Composite Primary key into simple primary key in thr table like this.
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.
We have a table, which has one clustered index and one non clustered index(primary key). I want to drop the existing clustered index and make the primary key as clustered. Is there any easy way to do that. Will Drop_Existing support on this matter?
Hi, How can I generate a sequence No. using a simple SELECT statement.
like
declare @key set @key = 1
SELECT @key, e.name from Employee
Now I want to display name of the employee and Key value which should get incremented automatically for each employee.. Is there any way? Please help me..
i've been asked to write a sql sequence for a database i'm building but i haven't been using SQL very long and i have no idea how to write a sequence. Does anyone know anything about sql sequences?
Hi,I need little help with Ms SQL Server 2000. I would like to know how tocreate sequence or something like that. I want to have an automatic counterfor each row in one entity, so then I can do something like this:INSERT INTO table VALUES (use sequence(something), value, value, .... )Can you please help me?thxTomas
CREATE TABLE [dbo].[property_instance] ( [property_instance_id] [int] IDENTITY (1, 1) NOT NULL , [application_id] [int] NOT NULL , [owner_id] [nvarchar] (100) NOT NULL , [property_id] [int] NOT NULL , [owner_type_id] [int] NOT NULL , [property_value] [ntext] NOT NULL , [date_created] [datetime] NOT NULL , [date_modified] [datetime] NULL )
I have created an 'artificial' primary key, property_instance_id. The 'true' primary key is application_id, owner_id, property_id and owner_type_id
In this specific instance - property_instance_id will never be a foreign key into another table - queries will generally use application_id, owner_id, property_id and owner_type_id in the WHERE clause when searching for a particular row - Once inserted, none of the application_id, owner_id, property_id or owner_type_id columns will ever be modified
I generally like to create artificial primary keys whenever the primary key would otherwise consist of more than 2 columns.
What do people think the advantages and disadvantages of each technique are? Do you recommend I go with the existing model, or should I remove the artificial primary key column and just go with a 4 column primary key for this table?
I have a SQL 2005 stored procedure to generate an email when passed parameters such as receipient, subject etc One of the paramteres passed to it is @body which is the body text of the message. I want to be able to add a couple of blank lines and then some footer information. This is working right now except I can't find the right way to add newlines into the string within the store procedure, so my footer information just tags right on after the bodytext. I have tried but that literally adds the two characters and n Can anyone advise how to generate newlien sequences in T-SQL. Regards Clive
