|
Mycroft Holmes wrote: (relearning) Oracle.
But not in C with Pro*C I bet.
|
|
|
|
|
PIEBALDconsult wrote: I have never understood the reason so many devs use the DataAdapter and load a whole butt-load of data at once when they don't use it all at once.
When you know there will never be too much data and that it will not have impact on system resources and when you want to work with data in a disconected state.
There are good uses for both approaches, that's why they exist. Beeing wise to use them where they fit is another story, can't speak for anyone.
|
|
|
|
|
If you are trying to update a value and you are already using the connection for reading data, you need to look at using a MARS connection (that's Multiple Active Result Set). Add MultipleActiveResultSets=true; to your connection string.
|
|
|
|
|
|
Tell us why one should NOT use stored procedures, as you state.
|
|
|
|
|
Using stored procedures, more of a good thing than using dynamic SQL? The article makes a good argument about changes legacy systems. The need to change the stored procedures will break code, or adding more stored procedures adds extra (duplicate) overhead. If just adding a new column to a table requires adding a new input parameter, we will need to add a new stored procedure to handle it. Of course, the old stored procedure can call the new stored procedure with a dummy argument for the new input value.
On the other hand, using dynamic SQL may require revision to add the new parameter (where it is needed). The down side is that legacy code that uses the database will need to have its SQL updated. Not only will the new application making use of the "improved" database have the changes, but all of the older applications will need to change, if the new database is used with them. And, there is the possibility of SQL injection attacks, depending on how you store your SQL in your application.
Updating Stored Procedures is akin to the old days of COM programming. There was a rule, at one time, that said we should not change a published interface, but make a new interface. This also was applied to the methods as well. And, a good programmer will do the least amount of work to get the job done efficiently.
You must decide which method is best for you.
|
|
|
|
|
It is maybe neater to not use a reader, but rather a DataTable and a TableAdapter. Then you can loop through the table rows, update the is_sent on each row as you process it, and then call Update. Something like this:
using (var ad = new SqlDataAdapter("sp_send_pending_sms", ConfigurationManager.ConnectionStrings["SQLdb"].ConnectionString))
{
ad.SelectCommand.CommandType = CommandType.StoredProcedure;
var dt = new DataTable();
ad.Fill(dt);
ad.AcceptChangesDuringUpdate = true;
ad.Update(dt);
}
If the list is long, you may want to call Update every n rows, not just at the end.
|
|
|
|
|
Yes, something like that is what you need. The ExecuteReader() method, as the name implies, is only for selecting (reading) data.
p.s. Stored procedures are a great way to go!
|
|
|
|
|
GamleKoder wrote: is only for selecting (reading) data.
No it isn't; it can execute any SQL statement (even a list of them if the particular database engine supports it) and it underlies all the other ADO.net data manipulation methody, so you're using it whether you know it or not.
|
|
|
|
|
You can not update through a DataReader. It retreives a read-only, forward-only stream of data one record at a time.
If I read your question correctly, you are doing some processing on each record after reading, then need to set a flag in the database to indicate that record has been processed.
You will need a second connection and comand object for this. You can't use the same connection/command as the DataReader because it keeps it's connection open internally throughout it's lifetime.
The best way to accomplish this will vary slightly depending on how many records you expect to process and whether the processing will run a long time (cumulative).
For a relatively short run:
1. Open SQLConnection for updating and attach to SQLCommand
2. Read next record from DataReader
3. Perform needed processing
4. Generate update SQL for current record
5. Use SQLCommand to run update SQL
6. Repeat steps 2 - 5 until last record has been processed and updated
7. Close and destroy update SQLConnection/SQLCommand
For a long run:
1. Create SQLConnection for updating and attach to SQLCommand
2. Read next record from DataReader
3. Perform needed processing
4. Generate update SQL for current record
5. Open SQLConnection for update
6. Use SQLCommand to run update SQL
7. Close SQLConnection
8. Repeat 2 - 7 until last record has been processed and updated
9. Close and destroy update SQLConnection/SQLCommand
Hope this answers your question and helps out.
Kevin Rucker, Application Programmer
QSS Group, Inc.
United States Coast Guard OSC
Kevin.D.Rucker@uscg.mil
"Programming is an art form that fights back." -- Chad Hower
|
|
|
|
|
Spectre_001 wrote: You can not update through a DataReader
No, but you can through ExecuteReader.
In your scenarios... generate a parameterized update command up front and then set the parameters for each row and execute -- no need to keep generating the same SQL statement.
|
|
|
|
|
That dosen't help if he needs to read, process, then update. 
Kevin Rucker, Application Programmer
QSS Group, Inc.
United States Coast Guard OSC
Kevin.D.Rucker@uscg.mil
"Programming is an art form that fights back." -- Chad Hower
|
|
|
|
|
Short answer - You can't. It is a data READER - not an updater. It's not like opening a recordset in VB6.
You need to ExecuteSQL with appropriate SQL to udpate the records (i.e. UPDATE table SET field=value WHERE key=id).
To do it the way you want it would better to use a DataSet or something a little more robust - plenty of info on MSDN.
|
|
|
|
|
Table-A is having 4 columns. I want to select values from Table-A with values from Event columns as column names as shown in Table-B. I need a stored procedure for selecting it if its possible.
TABLE-A
ID.No--Name-----Event-----------Amount_Paid
1---- Terry---ReliefFund------100
1---- Terry---Donation--------200
2---- John----Festival--------100
2---- John----Donation--------300
TABLE-B
ID.No---Name----ReliefFund------Donation--------Festival
1-------Terry---100-------------200-------------0
2-------John----0---------------300-------------100
Please help..., thanks
modified on Saturday, December 11, 2010 12:45 AM
|
|
|
|
|
For this what query you have developed?
What error it shows?
With Regards,
Kasson
|
|
|
|
|
|
SELECT * FROM mytable AS A
PIVOT (
SUM(AMOUNT)
FOR MEVENT IN([ReliefFund], [Donation], [Festival])
) AS M
|
|
|
|
|
This article [^]may be of use to you
Never underestimate the power of human stupidity
RAH
|
|
|
|
|
This Link[^] may help you.
|
|
|
|
|
I have an sql query which gives the output as follows:
OutputFileid
-----------
4
5
6
I want to get this output in horizontal fashion , like 4,5,6 so that I can pass to another query as an 'in' parameter.
I was getting that, but the second query returned an error saying that "Conversion failed when converting the varchar value '4,5,6' to data type int".
Following is the full stored procedure which i am using for getting the desired result.
ALTER procedure [dbo].[IsBCastRefExistsforProcess]
(@processId int)
as
begin
DECLARE @FILEIDs varchar(100)
select @FILEIDs= COALESCE(@FILEIDs+',' ,'')+ convert(varchar,outputfileid)+''from OutputFiles where ProcessId = @processid
PRINT @FILEIDs
if (LEN(@FILEIDs) > 0)
begin
select eg.EJVColumnId,eg.EJVColumnName
from EJVGedaColumns eg,
GedaColumnMapping gc
where eg.EJVColumnId = gc.EJVColumnId
and eg.EJVColumnName like '%BCAST_REF%'
and gc.OutputFileid in (@FILEIDs)
end
end
when I tried to execute exec IsBCastRefExistsforProcess 1234 it is giving the above error. Is there anyway which i can achieve this?
select @FILEIDs= COALESCE(@FILEIDs+',' ,'')+ convert(varchar,outputfileid)+''from OutputFiles where ProcessId = @processid
This gives me the values in horizontal fashion.
I tried giving 'and gc.OutputFileid in (Convert(int,@FILEIDs)) - But end up with same error.
Please help.
Thanks
Success is the good fortune that comes from aspiration, desperation, perspiration and inspiration.
|
|
|
|
|
I fixed it!!.
I put the same in a dynamic sql and it got worked. Like this,
SET @SQL = 'select eg.EJVColumnId,eg.EJVColumnName,gc.OutputFileid from EJVGedaColumns eg,GedaColumnMapping gc
where eg.EJVColumnId = gc.EJVColumnId and eg.EJVColumnName like ''%BCAST_REF%''
and gc.OutputFileid in ('+@FILEIDs+')'
EXEC (@SQL)
Hope this will help somebody.
Thanks
Success is the good fortune that comes from aspiration, desperation, perspiration and inspiration.
|
|
|
|
|
meeram395 wrote: EXEC (@SQL)
other then EXEC you can also use sp_executesql procedure that will give you a way to input parameter with a strong datatype to avoid data mismatch conflict.
|
|
|
|
|
Thanks very much Hiren, for the help. I will try that.
Success is the good fortune that comes from aspiration, desperation, perspiration and inspiration.
|
|
|
|
|
As an alternative; you could create a function that returns[^] a table (with those ints). You could pass these even as parameters[^] 
I are Troll 
|
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
