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Hi Nick
Re: ADO.NET : SqlDataReader : I need to assign retrieved value to C++ variable
I have found the source of the problem expressed in the thread "ADO.NET : SqlDataReader : I need to assign retrieved value to C++ variable":
http://www.codeproject.com/script/comments/forums.asp?forumid=3785#xx309754xx
but do not yet know why it occurs or how I can fix it.
The problem arises with the /clr compiler setting.
Here is the code to illustrate this:
/////////////////////////////////////////////////////////
#include <stdafx.h>
#include <cstdlib>
#include "try_ADONET.h"
//#using <mscorlib.dll>
//#using <system.dll>
//#using <system.data.dll> // This is required for the ADO.NET Provider
using namespace std;
//using namespace System;
int Main()
{
CString busNumberSQL[2];
CString bus = "Hello";
busNumberSQL[1] = bus;
return 0;
}
////////////////////////////////////////////////////////
Without the /clr setting the array of CString busNumberSQL[2] is correctly contructed as is CString bus and the line
busNumberSQL[1] = bus;
works as expected. This can be seen by putting a breakpoint in at
return 0;
and seeing the variables in a Watch. Copy the expanded Watch details (Name, Value & Type) to an EXCEL sheet.
..................
Next, add the compiler switch /clr and rerun the code.
CString bus is constructed correctly BUT something weird happens in the construction of CString busNumberSQL[2].
Now,
busNumberSQL[1] = bus;
results in the address of bus as an integer being assigned to busNumberSQL[1], and look at the Watch details!!
Copy the expanded Watch details (Name, Value & Type) to an EXCEL sheet
Name: busNumberSQL; Value: {Length=2}; Type: ATL::CStringT<char,strtraitmfc<char,atl::chtraitscrt<char> > >[] ...(Note no dimension at end compared to the "no /clr" case.
Next Watch line: [0] 2083454756 __int32
Next Watch line: [1] 3103464 __int32
My conclusion is that busNumberSQL[2] is not an array of CString.
Of course, I need the /clr in order to use ADO.NET!
It seems as though a CString works, but a CString array for some (unknown) cannot even be defined.
Do you have any light for me? (I have not got into your previous post yet on Marshall)
Best regards
Doug.
(In case you are wondering I am very much a beginner with C++ and .NET)
Doug
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what's wrong, tell me plz.
f:\projects center\task history\mission 8_13\hydrosrv\debug\msado15.tlh(530) : error C2011: 'ParameterDirectionEnum' : 'enum' type redefinition
Extreme programming. Do the No.1
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It looks like you are trying to #import the ADO stuff twice?
What does your #import line look like and where do you use it in your codd?
Michael
"I've died for a living in the movies and tv.
But the hardest thing I'll ever do is watch my leading ladies,
Kiss some other guy while I'm bandaging my knee."
-- The Unknown Stuntman
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Hi !
I'm totally new to Transact SQL. I've just been trying to familiarise myself with the below problem and struggling with it for last 6 hours without break.
Here is the schema
HOTEL (Hotel_No, Hotel_Name, Address)
GUEST (Guest_No, Guest_Name, Address)
ROOM (Room_No, Hotel_No, Type, Price)
BOOKING (Hotel_No, Guest_No, Date_From, Date_To, Room_No)
Where it asks what is the total income, for the month of July 2001, from occupied rooms at all the Sheridan Hotels.
How can i implement this in SQL? Or does any one have idea or hints.
Here is my attempmpt at it
<br />
DECLARE @NumberOfDay int<br />
<br />
IF (SELECT Hotel_Name FROM HOTEL WHERE Hotel_Name = 'Sheridan Hotel' and Address = 'Melbourne') = 'Sheridan Hotel'<br />
BEGIN<br />
PRINT 'Sheridan Melbourne'<br />
SELECT * FROM HOTEL h1, BOOKING b1, ROOM r1<br />
WHERE h1.Hotel_Name = 'Sheridan Hotel' <br />
and Address = 'Melbourne'<br />
and b1.Date_From < '2001-Jul-01'<br />
and b1.Date_To in (Select DatePart(07,01)= true<br />
<br />
END<br />
ELSE<br />
PRINT 'Sheridan Sydney'<br />
<br />
I'm trying to program it in SQL in SQL Analyzer, but i have never experienced programming with this transact SQL before. In the first instance, it is like Pascal to me, (IF ..END IF, BEGIN)
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--Store the first and last day of the month (July 2001)
DECLARE @StartMonth smalldatetime, @EndMonth smalldatetime
SELECT
--First of the month
@StartMonth = CAST('1 July 2001' As smalldatetime),
--Day before the first of the next month
@EndMonth = DATEADD(day, -1, DATEADD(month, 1, @StartMonth))
SELECT
--Hotel details
HOTEL.Hotel_No,
HOTEL.Hotel_Name,
HOTEL.Address,
--Total income per hotel
SUM(Bookings.Income) As Income
FROM
HOTEL INNER JOIN
(
--Calculate the income as Room price (per night) * # nights
SELECT
CASE
--Booking started before the month
WHEN Date_From < @StartMonth THEN
DATEDIFF(day, @StartMonth, Date_To) * ROOM.Price
--Booking finished after the month
WHEN Date_To > @EndMonth THEN
DATEDIFF(day, Date_From, @EndMonth) * ROOM.Price
--Booking was entirely within the month
ELSE
DATEDIFF(day, Date_From, Date_To) * ROOM.Price
END As Income
FROM
BOOKING INNER JOIN ROOM
ON ROOM.Room_No = BOOKING.Room_No
WHERE
--Only want bookings that intersect the month
Date_From < @EndMonth
AND
Date_To > @StartMonth
)
As Bookings
WHERE
--Only want bookings for the Sheridan hotels
Hotel_Name = 'Sheridan Hotel'
GROUP BY
HOTEL.Hotel_No,
HOTEL.Hotel_Name,
HOTEL.Address
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Hi!
Your answer has resolved and swept away alot of mysterious things that were in my head! I highly appreciate your it.
Thank you very much
Regard,
Ps: it gives me error say near the "WHERE" keyword, but i am still attempting to fix it!
Server: Msg 156, Level 15, State 1, Line 48
Incorrect syntax near the keyword 'WHERE'.
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--Store the first and last day of the month (July 2001)
DECLARE @StartMonth smalldatetime, @EndMonth smalldatetime
SELECT
--First of the month
@StartMonth = CAST('1 July 2001' As smalldatetime),
--Day before the first of the next month
@EndMonth = DATEADD(day, -1, DATEADD(month, 1, @StartMonth))
SELECT
--Hotel details
HOTEL.Hotel_No,
HOTEL.Hotel_Name,
HOTEL.Address,
--Total income per hotel
SUM(Bookings.Income) As Income
FROM
HOTEL INNER JOIN
(
--Calculate the income as Room price (per night) * # nights
SELECT
ROOM.Hotel_No,
CASE
--Booking started before the month
WHEN Date_From < @StartMonth THEN
DATEDIFF(day, @StartMonth, Date_To) * ROOM.Price
--Booking finished after the month
WHEN Date_To > @EndMonth THEN
DATEDIFF(day, Date_From, @EndMonth) * ROOM.Price
--Booking was entirely within the month
ELSE
DATEDIFF(day, Date_From, Date_To) * ROOM.Price
END As Income
FROM
BOOKING INNER JOIN ROOM
ON ROOM.Room_No = BOOKING.Room_No
WHERE
--Only want bookings that intersect the month
Date_From < @EndMonth
AND
Date_To > @StartMonth
)
As Bookings
ON Bookings.Hotel_No = HOTEL.Hotel_No
WHERE
--Only want bookings for the Sheridan hotels
Hotel_Name = 'Sheridan Hotel'
GROUP BY
HOTEL.Hotel_No,
HOTEL.Hotel_Name,
HOTEL.Address
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I have a view that joins a table back on itself like the following SQL
select pm.portfolio_code master_code
,pp.portfolio_code part_code
from portfolio pm
,portfolio pp
where pm.master_account_indicator = 1
and pp.master_account = pm.portfolio_code
order by pm.portfolio_code, pp.portfolio_code
This produces some results like this
MASTER_CODE PART_CODE
----------- ----------
17 7
17 12
17 14
227 226
286 246
286 287
293 45
293 440
Could someone suggest what has to be added so that a third colum gives me an incremented count of the master_code column. The result should be like this
MASTER_CODE PART_CODE INC_COUNT
----------- ---------- ---------
17 7 1
17 12 2
17 14 3
227 226 1
286 246 1
286 287 2
293 45 1
293 440 2
I know how I can provide the data in some C++ code that will process the rows returned from the view, but I would really like to have the SQL do it for me.
Thanks for any suggestions.
Chris Meech
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I think you can only do this with cursors and a temp table.
Signature space for rent. Apply by email to....
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Assuming SQL Server 2000:
DECLARE @temp TABLE (
MASTER_CODE int not null,
PART_CODE int not null,
INC_COUNT int not null DEFAULT 0
)
INSERT INTO
@temp (MASTER_CODE, PART_CODE)
SELECT
pm.portfolio_code, pp.portfolio_code
FROM
portfolio As pm INNER JOIN portfolio As pp
ON pp.master_account = pm.portfolio_code
WHERE
pm.master_account_indicator = 1
ORDER BY
pm.portfolio_code, pp.portfolio_code
DECLARE @Count int, @Previous int
SELECT @Count = 1, @Previous = Null
UPDATE @temp
SET
@Count = INC_COUNT = CASE
WHEN MASTER_CODE = @Previous THEN @Count + 1
ELSE 1
END,
@Previous = MASTER_CODE
SELECT
MASTER_CODE,
PART_CODE,
INC_COUNT
FROM
@temp
ORDER BY
MASTER_CODE,
PART_CODE
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Thanks for the suggestions. This morning, I finally got the view to do what I wanted. With the knowledge that the portfolio_code column of the portfolio table is a unique identifier for each row, I got the following SQL to run and do exactly what I was looking for.
select pm.portfolio_code master_code
,pp.portfolio_code part_code
,( select count(c.portfolio_code) from portfolio c
where c.portfolio_code <= pp.portfolio_code
and c.master_account = pm.portfolio_code
) inc_count
from portfolio pm
,portfolio pp
where pm.master_account_indicator = 1
and pp.master_account = pm.portfolio_code
order by pm.portfolio_code, pp.portfolio_code
Essentially, as each row is returned, another query runs and returns the count of portfolio_code that is less than or equal to the value in the row being returned.
Chris Meech
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I always used the SELECT Count(*) AS nCount syntax to select the number of records which have the specified requirements. But yesterday, while giving a look to some example code, I found the SELECT Count(1) AS nCount syntax. Is this different from the first one? If yes, which one is the faster?
Luca Leonardo Scorcia
http://zip.to/kojak (only in Italian)
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select count(1) is quicker, there is less data to shift about. compare the query plan for each one in query analyser and you'll see the point.
only really makes a difference on large-ish tables (100,000+ records or so)
Signature space for rent. Apply by email to....
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my mistake, i meant server trace.
there's not that much difference between the two forms though.
And, in sql server, the quickest way to get a rowcount of a whole table is to use sp_spaceused
Signature space for rent. Apply by email to....
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What's this Query Analyser? Is it included in SQL Server? Because I'm using SQL on an Access DB via ADO... but if it's a standalone tool it could be very useful!!!
Luca Leonardo Scorcia
http://zip.to/kojak (only in Italian)
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Oh, only in SQL Server, and it uses some nice SQL Server features, like showing the query plan, and so on...
If you go serious about database development, you should really consider using SQL Server. There's even a free version of SQL Server, named MSDE or SQL Desktop Engine. Try it, is nice...
My latest articles:
Desktop Bob - Instant CP notifications
XOR tricks for RAID data protection
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I have tried to store more than 255 chars in an Access 2000 database, but it isn't allowed!
How can I stor more than 255 chars in Access?
I beleive it's not possible!?
Rickard Andersson@Suza Computing
C# and C++ programmer from SWEDEN!
UIN: 50302279
E-Mail: nikado@pc.nu
Speciality: I love C#, ASP.NET and C++!
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Hi Rickard.
Rickard Andersson wrote:
I beleive it's not possible!?
No.Use Memo type.
Mazy
"If I go crazy then will you still
Call me Superman
If I’m alive and well, will you be
There holding my hand
I’ll keep you by my side with
My superhuman might
Kryptonite"Kryptonite-3 Doors Down
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Mazdak wrote:
Use Memo type
Okay, but how do I do that?
I opened my table in Access 200 in Design mode and checked if Memo type could be used for my field, but no.... 
Can you explain more?
Thank you very much!
Rickard Andersson@Suza Computing
C# and C++ programmer from SWEDEN!
UIN: 50302279
E-Mail: nikado@pc.nu
Speciality: I love C#, ASP.NET and C++!
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Rickard Andersson wrote:
I opened my table in Access 200 in Design mode and checked if Memo type could be used for my field, but no....
The Memo field is listed under the data type section of your database.
Nick Parker
The greatest lesson in life is to know that even fools are right sometimes. - Winston Churchill
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Nick Parker wrote:
The Memo field is listed under the data type section of your database.
Found it!
In the Swedish edition Memo = PM (which is the same anyway )
Rickard Andersson@Suza Computing
C# and C++ programmer from SWEDEN!
UIN: 50302279
E-Mail: nikado@pc.nu
Speciality: I love C#, ASP.NET and C++!
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I have a treeview that is populated from a self joined table in a way analogus to that detailed by Gevik in his article:
http://www.codeproject.com/useritems/2dtreeview.asp#xx281692xx[^]
Now I've been trying to work out the most efficent way to delete a from the treeview and have the corresponding node in the database, plus any children, be deleted. I tried this:
private void CascadeDelete(int iParent)
{
DataView dvView = new DataView(dsData.Tables[0]);
dvView.RowFilter = "ParentID = '" + iParent + "'";
while (dvView.Count>0)
{
DataRowView thisRow = dvView[0];
int thisID = Int32.Parse(thisRow["TypeID"].ToString());
CascadeDelete(thisID);
MessageBox.Show("DELETING: " + thisRow["strType"].ToString());
thisRow.Delete();
}
}
The problem, I think, is that as the recursion unwinds the DataRowView of the caller is out of date because the callee has changed it, but trying to update it again (by uncommenting the above lines) doesn't seem to work. The end result is that when I try to call dsData.GetChanges() it returns null.
Here's a example of the messed up recursion, give the nodes:
1
|-3
|-2
|-6
|-5
| |-7
4
I get this series of "deletion": 3,6,7,7,5,4,6,5,4,2,3,2
Any ideas on an efficient (or even just working!) way to do this? I could just issue a bunch of individual SQL statements to delete each row, but that seems horribly inefficient.
Thanks
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Sorry, can you explain what you mean?
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