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Oh, I think I got your point now.
What you are saying is keep dates in a permanent table ( for a long dates, eg: 2000-01-01 to 2500-01-01) and use that table to join with the other table in the date range I want to.
I appreciate your help all the time...
CodingLover 
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Exactly
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Thanks buddy.
I'll give a try and let you know.
So I'll keep this thread as it is.
I appreciate your help all the time...
CodingLover
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Step 1: Create a table variable with a date column and fill the table with the date range that you need (probably the min and max dates from 'packages' table)
Step 2: Use your query and do a union with the temp table created in step 1
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Shameel wrote: Step 1: Create a table variable with a date column and fill the table with the date range that you need (probably the min and max dates from 'packages' table)
So I can move with a temporary table or a permanent one. But I'm stuck with how to insert range of dates into it. Something like this ...
CREATE TEMPORARY TABLE date_col (add_dates nvarchar(50));
INSERT INTO date_col (add_dates) VALUES ('2011-04-06' through '2011-04-01');
I appreciate your help all the time...
CodingLover
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Hi all,
My web application base on money transactions. My client wants to keep a realtime backups. That means i host the web app in one server and have another server for backups. If system down in the hosted server there is a backup link to the system in backup server. The problem is i want to update the backup server database in the same time when updating the original server database. What is the best and more efficient solution for this requirement.
thanks
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This is a standard setup for a high a proficiency site, you need mirroring (as Mika suggested) and more probably failover web and database servers. I would suggest talking to a hosting site, it may be simpler to pay someone else to do these.
Never underestimate the power of human stupidity
RAH
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Good addition Marked as good answer.
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In our application the user can define custom "user defined type" called "data context" to store a bunch of named datetime/string/number/list(Guid)
such as (for example)
--
Contact Information
Name
Age
Address
Birthday
--
we store that in the DB with some table like that (simplified version)
Sets -- a such item, ex: a contact information
id Guid
idDef Guid -- PK to the type definition table
SetValues -- store the values, ex: Contact.Name
id Guid
idSet Guid -- PK to a record in Sets
idDef Guid -- PK to the type definition table
Value sql_variant
In fact it's a it more complicated (deep) due to list and list with property (2 more tables to store the value of a single user type value)
The problem is it's quite cumbersome to do a search for a value for example and we were thinking to store the data instead, in a table like that
Sets
id Guid
string1 nvarchar(max)
...
string15 nvarchar(max)
datetime1 datetimeoffset(7)
..
datetime15 datetimeoffset(7)
number1 decimal(8,2)
..
number15 decimal(8,2)
list1 uniqueidentifier
..
list15 uniqueidentifier
I'm not sure I explain my problem clearly but.. what I wonder is: is there a clever schema that will allow to store the untyped hierarchical user data, yet makes it easy to join / search, etc...
A train station is where the train stops. A bus station is where the bus stops. On my desk, I have a work station....
_________________________________________________________
My programs never have bugs, they just develop random features.
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Hi,
If I understood you correctly, you have already created tables where you can handle dynamic amount of attributes and values. Querying such tables is often a bit tricky if you have several levels etc, but CTE[^] is a helpful tool when handling dynamic hierarchies.
On the other hand another possibility could be to use XML data type. This would allow you flatten the relational hierarchy and still be able to use highly dynamic values.
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Yeah, XML data type, someone mentioned that... Have to have a look, thanks!!
I though I knew about CTE already but.. didn't know ou can use them for recursive queries!!! mm... thanks (again!)!
A train station is where the train stops. A bus station is where the bus stops. On my desk, I have a work station....
_________________________________________________________
My programs never have bugs, they just develop random features.
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No problem
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Hi guys, I've learnt 'bout database designing and I got a difficulty that you can help.
Here the question is: a relation R has 3 attributes, A,B,C and A is a primary key. Then I want to insert new attribute D. In each tuple of R, value of attribute D is assigned by (value of B + value of C).
My task is using Relational algebra, writing a expression to do so.
Below is an example
R - before doing anything
A B C
1 10 9
2 3 7
3 9 6
4 12 0
5 1 5
R - after inserting attribute D
A B C D
1 10 9 19
2 3 7 10
3 9 6 15
4 12 0 12
5 1 5 6
Anyway, thanks alot for reading my question and helping my solve this problem
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It's not quite clear what your actual question is but concerning calculated columns. It's typically best to avoid columns which are calculations based on the values of the same (or other) rows. This is because you have to take care that when the original values change, also the result of the calculation is changed.
If you're using SQL Server, then things are a bit different since the database has the ability to use computed columns (see: http://msdn.microsoft.com/en-us/library/ms191250.aspx[^]).
If your question is about updating the value, then:
- first insert the new column
- then update the existing rows. Something like:
UPDATE R
SET D = A + B
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Duc Huy Nguyen wrote: My task is using Relational algebra, writing a expression to do so.
That sounds complicated. I'd rephrase that to "you need to add a column to the table, that holds the sum of columns B + C". You'd need to alter the table[^], ending up with something like this;
BEGIN TRAN
CREATE TABLE [R]
(
A INT,
B INT,
C INT
)
INSERT INTO [R]
SELECT 1, 10, 9 UNION ALL
SELECT 2, 3, 7 UNION ALL
SELECT 3, 9, 6 UNION ALL
SELECT 4, 12, 0 UNION ALL
SELECT 5, 1, 5
ALTER TABLE [R]
ADD D AS [B] + [C]
SELECT *
FROM [R]
ROLLBACK
I are Troll 
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You shouldn't include calculated columns in your table like this, IIRC it breaks first normal form as the columns are no longer atomic. You should put the calculation into your select statements -or- [better] create a View with the calculated column in it.
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May I ask how it's no longer atomic? The "new" value (the result from the calculation) is a new atomic fact, even though it's derived from other data - it's not a concatenation of both original columns and you cannot deduce the original values from it.
I are Troll
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Eddy Vluggen wrote: May I ask how it's no longer atomic?
The calculated column relies on other data, it isn't atomic. The classic examples use concatenation, but it is realy a relies upon relationship.
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Keith Barrow wrote: The calculated column relies on other data, it isn't atomic
It relies on other data, that's true, but you cannot decompose the value. It's a new atomic fact, not a composition of other facts. Yes, you can deduce it from other data, but in this case only in one direction (as opposed to a birthdate and an age)
Keith Barrow wrote: The classic examples use concatenation, but it is realy a relies upon relationship.
Any concatenation of characters would fall under this category. The question is whether the fact that's being described is atomic, not the data.
Whether or not a column is computed (and whether or not the value is stored or recomputed), doesn't matter much for the relational model; that's merely an implementation-detail.
I are Troll
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Hmmmm, I get your point, but I don't undertand how:
"hello " + "world" = "hello world"
Is not a new fact, but:
2 + 5 = 7
is.
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That's not information, that's data. I can't model data. Your first example may be a single fact, contained in a varchar field. The second might be too, but could just as well be a derived fact. Like having two apples and five banana's equalling seven pieces of fruit. The numbers of fruit in store is a different fact, and it might be fetching totals from an apple-database and a banana-database.
An atomic piece of data is a bit. An atomic piece of information, is dependent on context - the key of the table.
Take a look at your name - under what circumstance would you see the "data" as a single entity of atomic data? Which different parts of your name are used under those circumstances?
I are Troll
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In the relational model, there is is no concept of DEcompose the value !
If a value can be composed from other values, COMPOSE it, or you will denormalize the DB !!!
This is (should be) only allowed, if the normal form takes some time for calculation, and the application is time critical.
If this is the case, you should use INSERT and UPDATE triggers to ensure the data consistence
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