refresh identity value

hi,
how can I refresh a identity value of a table after a record gets deleted.

for example a table has 100 rows. One of its column name is rowIndex set to identity 1, incremental 1. After I remove the row with rowIndex value 100, if I insert a new record the rowIndex will be 101, but I want its rowIndex value to be 100. Is there a way to update the identity value after a record gets removed?Yes, but that's not the intention of an identity column. An identity column is intended to automaticaly give you unique record ids.

If you want your rowindex to represent something else then add a trigger to get the max(rowindex) and then add 1.sql

Referential Integrity - linking multiple tables to transaction table

I have transaction table where the rows entered into the transaction
can come a result of changes that take place if four different tables.
So the situation is as follows:

Transaction Table
-TranId
-Calc Amount

Table 1 (the amount is inserted into the transaction table)
- Tb1Id
- Tb1Amt

Table 2 (an amount is calculated based on the percentage and inserted
into the transaction table)
-Tbl2Id
-Tb2Percentage

Table 3 (the amount is inserted into the transaction table)
-Tbl3Id
-Tbl3Amut

Table 4 (an amount is calculated based on the percentage and inserted
into the transaction table. )
-Tbl2Id
-Tb2Percentage

How do I create referential integrity between the Transaction table and
the rest of the tables. When I make changes to the values in Table 1 -
4, I need to be able to reflect this in the Transaction table.

Thanks.Can you make "Transaction Table" into a view
based on joins between your other 4 tables?

Where does TransID come from?|||Thanks,

Trans ID is generated - identify column.

We thought of using a view. But the when the core object is set to
LIVE, all changes from then on will be tracked as new transactions in
the transaction table. So in essence, you have have a row in Table 1 -
4 that has multiple transactions in the transacation table. We could
add a column to the Transaction Table set it to refer to the Ids of
Table 1 - 4. But we won't be able to use the DBMS contraints to enfore
this. Possibly a middle table to each Table 1 to 4?|||(heyvinay@.gmail.com) writes:
> I have transaction table where the rows entered into the transaction
> can come a result of changes that take place if four different tables.
> So the situation is as follows:
> Transaction Table
> -TranId
> -Calc Amount
> Table 1 (the amount is inserted into the transaction table)
> - Tb1Id
> - Tb1Amt
> Table 2 (an amount is calculated based on the percentage and inserted
> into the transaction table)
> -Tbl2Id
> -Tb2Percentage
> Table 3 (the amount is inserted into the transaction table)
> -Tbl3Id
> -Tbl3Amut
> Table 4 (an amount is calculated based on the percentage and inserted
> into the transaction table. )
> -Tbl2Id
> -Tb2Percentage
> How do I create referential integrity between the Transaction table and
> the rest of the tables. When I make changes to the values in Table 1 -
> 4, I need to be able to reflect this in the Transaction table.

Depends on what you mean with changes, but obviously if you change an
amount in one table and you want that to affect the CalcAmount in the
Transaction table, then you should consider a trigger. For that to
work, the Transaction table need to have one FK column per referencing
table.

Your description was quite brief, and very abstract. It is not at all
impossible that there is a better design, if you can give more meat of
what is behind the various tables.

--
Erland Sommarskog, SQL Server MVP, esquel@.sommarskog.se

Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/pr...oads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodin...ions/books.mspx|||Thanks.
Well the application we are designing is for Premium calcuation. The
transaction table will store all the premium calcuation breakdowns.
The reference to table 1 - 4 are various elements within the system
that will generated chargeable premiums. Eg. the product selected;
discounts applied to the customer; specific endorsements; Payment
menthod discounts etc. Once policy is live, and changes to the source
tables (eg product, discount amount) etc or even the cancellation of
the policy will raise NEW records in the transaction tables.

We can manage all this from code directly to ensure all is in sync, but
I prefer to apply referential integrity managed by the DBMS.

You wrote: "For that to work, the Transaction table need to have one FK
column per referencing table. " - does MS SQL allow null values for
foreign key constraints?

Thanks|||(heyvinay@.gmail.com) writes:
> We can manage all this from code directly to ensure all is in sync, but
> I prefer to apply referential integrity managed by the DBMS.

Referential integrity is about the integrity of - references. That is,
if the Orders table has a FK constraint to table Customers, you cannot
add an Order for a non-existing customer, and you cannot delete a customer
that has an order.

As I understood it, you want one data in one table be the result of data
in other tables. This cannot be achieved with referential integrity. You
can use views, and under some circumstances you can materialise a view.

> You wrote: "For that to work, the Transaction table need to have one FK
> column per referencing table. " - does MS SQL allow null values for
> foreign key constraints?

Yes. For instance, in a Customers table, you may have Citizen column
table that has a foreign-key constraint to the Countries table. But
this column must be nullable, since some people stateless. Not talking
of juridical persons, who normally are not citizens.

--
Erland Sommarskog, SQL Server MVP, esquel@.sommarskog.se

Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/pr...oads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodin...ions/books.mspx|||Off the top of my head, two fundamental ways.

Insert into the 4 tables, and have triggers on those tables for insert,
update, and delete that add rows to the trans table.

Two. utilize standardized stored procedures you use to add/edit/update
the 4 tables. Inside the stored procedures, do a begin trans/ commit
around the changes and the trans table. In this way, you can pretty
much ensure that it will keep up.

The stored procedure has the advantage of allowing more business logic
around changes. You can validate data changes external to the app.
However, you MUST enforce that all changes to the 4 tables MUST uses
the specified stored procedures.

The Triggers have the advantage of "simplicity." Again though,. you are
somewhat limited in what logic you can use.

Two comments you didn't ask for. Be very stingy with indexes on the
trans table. I'm not saying ot have none, BUT don't have a lot of
indexes. And the indexes you do have should be fairly unique. Trans
tables get very large very fast, and they really slow everything down
in a sneaky insidious sort of way in a few years.

Secondly, it can be hard to get the :"right" infomration into the trans
table. As a test to see whether you have all data you need, manually
try to take each trans record, and recreate the final data results. In
a perfect world, your trans table will allow a picture of exactly what
changed when and how, allowing hte final results to be seen.
For a final test, just go ahead and write the program that will read
the trans data and recreate teh table. This is almost never trivial,
but almost always worthwhile.
-dougsql

Reference previously calculated values in a table between rows

I have a requirement where I produce a number of rows in a table footer and each subsequent rows needs values calculated in the previous row. Fields in columns can be given a name and used in another column of the same row by using "=ReportItems!textbox1.Value".
Is the same thing available between rows?
Thanks for any help.You can refer to the previous value of fields (expressions) in table rows.
Try e.g.:
=Previews(Fields!abc.Value)
--
This posting is provided "AS IS" with no warranties, and confers no rights.
"lsff" <lsff@.discussions.microsoft.com> wrote in message
news:C73A4807-BCE9-4B58-A2FC-4E894C07A30D@.microsoft.com...
> I have a requirement where I produce a number of rows in a table footer
and each subsequent rows needs values calculated in the previous row. Fields
in columns can be given a name and used in another column of the same row by
using "=ReportItems!textbox1.Value".
> Is the same thing available between rows?
> Thanks for any help.|||Sorry, I meant:
=Previous(Fields!abc.Value)
--
This posting is provided "AS IS" with no warranties, and confers no rights.
"Robert Bruckner [MSFT]" <robruc@.online.microsoft.com> wrote in message
news:uA75dBFdEHA.3148@.TK2MSFTNGP10.phx.gbl...
> You can refer to the previous value of fields (expressions) in table rows.
> Try e.g.:
> =Previews(Fields!abc.Value)
> --
> This posting is provided "AS IS" with no warranties, and confers no
rights.
>
> "lsff" <lsff@.discussions.microsoft.com> wrote in message
> news:C73A4807-BCE9-4B58-A2FC-4E894C07A30D@.microsoft.com...
> > I have a requirement where I produce a number of rows in a table footer
> and each subsequent rows needs values calculated in the previous row.
Fields
> in columns can be given a name and used in another column of the same row
by
> using "=ReportItems!textbox1.Value".
> >
> > Is the same thing available between rows?
> >
> > Thanks for any help.
>|||Robert,
This didn't do what I needed. For example, I have a field which contains a sum of different values (call it field A). In the next row, I calculate a value based on field A and another field in a different dataset (call this field B). In the third row, I want the total of Fields A and B (call this Field C). At the moment, I include in Field C the formula for field A and add to it the formula from Field B. I have a number of other rows wioth progressive additions. So you can see the formula in the fields keep on getting bigger and bigger. It would be nice to just say Field A + Field B, etc.
"Robert Bruckner [MSFT]" wrote:
> Sorry, I meant:
> =Previous(Fields!abc.Value)
> --
> This posting is provided "AS IS" with no warranties, and confers no rights.
> "Robert Bruckner [MSFT]" <robruc@.online.microsoft.com> wrote in message
> news:uA75dBFdEHA.3148@.TK2MSFTNGP10.phx.gbl...
> > You can refer to the previous value of fields (expressions) in table rows.
> > Try e.g.:
> > =Previews(Fields!abc.Value)
> >
> > --
> > This posting is provided "AS IS" with no warranties, and confers no
> rights.
> >
> >
> > "lsff" <lsff@.discussions.microsoft.com> wrote in message
> > news:C73A4807-BCE9-4B58-A2FC-4E894C07A30D@.microsoft.com...
> > > I have a requirement where I produce a number of rows in a table footer
> > and each subsequent rows needs values calculated in the previous row.
> Fields
> > in columns can be given a name and used in another column of the same row
> by
> > using "=ReportItems!textbox1.Value".
> > >
> > > Is the same thing available between rows?
> > >
> > > Thanks for any help.
> >
> >
>
>

Reference an aggregate in where clause

I have two tables that are joined on 1 column.

I want to update one table using an aggregate from the other table.

I could just update all rows even if the aggregate value has not changed, but I wondered if there was a way to only update the records where the aggregate has changed.

I tried this code but assigning the name m to aggreate gives an error

UPDATE t2 SET t2.ColumnB = SELECT MAX(ColumnB) AS m From Table t1

JOIN t2 ON t1.ColumnA = t2.ColumnA

WHERE t2.ColumnB <> m

GROUP BY t1.ColumnA

Niall:

Does this meet your needs?

set nocount on

declare @.t1 table (ColumnA char(1), ColumnB int)
declare @.t2 table (ColumnA char(1), ColumnB int)

insert into @.t1 values ('A', 5)
insert into @.t1 values ('B', null)
insert into @.t1 values ('C', null)
--select * from @.t1

insert into @.t2 values ('A', 3)
insert into @.t2 values ('A', 5)
insert into @.t2 values ('A', 7)
insert into @.t2 values ('B', 2)
--select * from @.t2

set nocount off

update @.t1
set ColumnB = xt.columnb
from @.t1 as yt
inner join
( select t1.ColumnA,
max (t2.columnB) columnB
from @.t1 as t1
inner join @.t2 as t2
on t1.columnA = t2.columnA
group by t1.columnA
) xt
on xt.columnA = yt.columnA

set nocount on

select * from @.t1

-- --
-- Output
-- --

-- (2 row(s) affected)

-- ColumnA ColumnB
-- - --
-- A 7
-- B 2
-- C NULL

|||

Use a subquery - replace the 0 in the isnull calls with blank strings if your ColumnB is character data.

UPDATE Table2 SET ColumnB = t1.MaxB
FROM Table2 t2
INNER JOIN
(SELECT ColumnA, MAX(ColumnB) AS MaxB
FROM Table1
GROUP BY ColumnA) t1 ON t2.ColumnA = t1.ColumnA
WHERE isnull(t2.ColumnB, 0) <> isnull(t1.MaxB, 0)

Reducing filesize while deleting rows?

I've got a very filesize restricted database. I noticed that when I insert 1000 rows my filesize jumps to 80k, but when I delete all but 50 of those rows...the filesize actually increases to 84k. How do I make sure the filesize of my database shrinks when I delete rows?

Thanks!

Use SqlCeEngine.Compact() or SqlCeEngine.Shrink() to do that. You can find description on MSDN.

|||Unfortunately I'm using native C++ for all this, so I don't have access to SqlCeEngine. Is there a SQL command i could execute to perform the equivalent to a shrink routine? If that doesn't exist I'll need some way to do it while an existing OLEDB connection is open and operating. I need this database to run 24/7 with no downtime whatsoever.

Thanks for the help!
|||

The database connection must be closed to do shrink or repair. This is a design requirement so that database file structure can be recreated.

What you can probably do is to make a copy of the database , compact it, momentarily drop connection to original database and replace original with compacted database. You will have to take a read only lock on original db while the copy is compacted so that no new changes take place.

|||

The OLEDB provider has an Engine object, which has a CompactDatabase method.