|
Is there a document somewhere (yes i've looked) that lists the restrictions/limitations for different cursor types.
I'm mainly looking for something in an ODBC context but would be happy enough with SQLSrv specific.
I have seen: http://blogs.msdn.com/mssqlisv/archive/2006/06/23/644493.aspx
"Generally, a (FAST) FORWARD-ONLY cursor is the most performant, followed by DYNAMIC, KEYSET, and finally STATIC which is generally the least performant.
For example, if a FAST FORWARD ODBC API Server Cursor referenced a text column, it would typically degrade to a DYNAMIC cursor, however if the query also generates an internal work table because an ORDER BY condition is not covered by an index, then the cursor would degrade to a KEYSET cursor. If at this point the query also referenced a table without a unique index the cursor degraded further to a STATIC cursor. This is an extreme example; however it illustrates the sequence of events that previous versions of SQL Server used to degrade a cursor to a progressively 'more expensive' cursor
type."
This is great, but i expect incomplete.
Nor does it explain why a text column would cause a forward-only cursor to
'degrade', or ...
...cmk
Save the whales - collect the whole set
|
|
|
|
|
I think the only decent answer you'll get will be from the Microsoft SQL Server team. I'm assuming that you don't already have a blogs.msdn.com profile. On the top-left of the page click Sign In, then follow the screens to create a profile and log in. Once you've done this you'll be able to leave a comment on that blog entry.
I suspect it's something like that: FAST FORWARD ONLY cursors only work if all the data is in-row - text, ntext and image columns are stored externally, on a different database page, to the normal data (the row contains a pointer to the text/ntext/image data). A DYNAMIC cursor only works if the data is in the order it comes from the database tables but can cope with off-row data. A KEYSET cursor requires that there's a primary key value available for the data (the cursor data consists of the set of keys). A STATIC cursor is just a complete copy of the results retrieved.
|
|
|
|
|
Thanks Mike, your remarks are in line with what i was thinking.
I'll take a look a the blog page sign-in.
The only reason this is an issue as some C++/ODBC code broke (a couple queries) moving from SQL Srv 2000 to Sql Srv 2005. It turns out some cursors that were being silently degraded aren't anymore. As such i want to get a better handle on what they sould be to start with.
Again, thanks
cmk
[EDIT]
FYI, Just fuond:
http://msdn2.microsoft.com/en-us/library/ms190641.aspx[^]
[/EDIT]
-- modified at 18:53 Monday 24th July, 2006
|
|
|
|
|
May i know what is the problem in my code below?
Private Sub Button1_Click(ByVal sender As
System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Try
If TextBox1.Text <> "" Then
Dslogin1.Clear()
OleDbDataAdapter1.SelectCommand.CommandText = _
"SELECT * FROM Login WHERE username = " &
TextBox1.Text & ""
OleDbDataAdapter1.Fill(Dslogin1, "Login")
DataGrid1.SetDataBinding(Dslogin1,"Login")
End If
Catch e1 As Exception
MessageBox.Show(e1.ToString)
End Try
End Sub
i cant search the username from the textbox1.
|
|
|
|
|
ghost181 wrote: OleDbDataAdapter1.SelectCommand.CommandText = _
"SELECT * FROM Login WHERE username = " &
TextBox1.Text & ""
Include Quotation marks:
OleDbDataAdapter1.SelectCommand.CommandText = _
"SELECT * FROM Login WHERE username = '" &
TextBox1.Text & "'"
_____________________________
Success is not something to wait for, its something to work for.
|
|
|
|
|
Ignore the last response because he doesn't actually solve your real problem. Your real problem is the code is susceptable to a SQL Injection Attack.
You should use parameterised queries. e.g.
OleDbDataAdapter1.SelectCommand.CommandText =
"SELECT * FROM Login WHERE username = ?";
OleDbDataAdapter1.SelectCommand.Parameters.Add("", TextBox1.Text);
This will go some way to protecting your database from attack.
You will want to read SQL Injection Attacks and Tips on How to Prevent Them[^] which tells you what a SQL Injection Attack is, how to spot code that is susceptable and how to correct the problem.
|
|
|
|
|
Thanks Colin Angus Mackay, i solve the problem already.
|
|
|
|
|
Colin Angus Mackay wrote: SQL Injection Attacks and Tips on How to Prevent Them[^] which tells you what a SQL Injection Attack is, how to spot code that is susceptable and how to correct the problem.
As often as that article is referenced why not just include it in your sig?
I'd love to help, but unfortunatley I have prior commitments monitoring the length of my grass. :Andrew Bleakley:
|
|
|
|
|
S Douglas wrote: As often as that article is referenced why not just include it in your sig?
I don't currently have room. I'll consider it when space frees up a bit.
|
|
|
|
|
Hi, i don't know if is possible to do this: I want to obtain by a single query, values from 2 identical tables, ok, i can do a query from multiple tables and that will return values with no problem BUT these values are returned horizontally but how can i get these values vertically, i hope you understand the terms horizontally and vertically. If you think what i'm trying to do, is to execute 2 queries in 1.
Example:
select t1.col1, t2.col1 from table1 as t1, table2 as t2
-> 1, 2
-> 4, 7
-> 8, 9
but how can i get this?
-> 1
-> 2
-> 4
-> 7
-> 8
-> 9
or this
-> 1
-> 4
-> 8
-> 2
-> 7
-> 9
|
|
|
|
|
SELECT t1.col1 FROM table1 AS t1
UNION
SELECT t2.col1 FROM table2 AS t2
--EricDV Sig---------
Some problems are so complex that you have to be highly intelligent and well informed just to be undecided about them.
- Laurence J. Peters
|
|
|
|
|
|
Can anyone tell what is wrong with this select statement?
Select Statement:
***************************************************
SELECT [Primary Number] FROM [Vital Stats] WHERE [Title-D] IS NULL OR [First Name-D] IS NULL OR
[Last Name-D] IS NULL OR [Inform Title] IS NULL OR [Inform first Name] IS NULL OR
[Inform Last Name] IS NULL OR [Address-infor-1] IS NULL OR [City/town-infor] IS NULL OR
[State-infor] IS NULL OR [ZipCode-infor] IS NULL OR [Inf RevRel] IS NULL OR [Director Name] IS NULL IN(selectedCases)
***************************************************
I'm using VB .NET and the data is being pulled (or should be pulled I should say) from an ACCESS Database
I keep getting this error message:
"Invalid use of IS operator in query expression [Title-D] IS NULL OR [First Name-D] IS NULL OR...."
I want to pull the records that contain a NULL value in any of those fields listed in the select statement.
Any suggestion is valid, since I can't get it to work.
Thank you,
silvionr
|
|
|
|
|
silvionr wrote: IS NULL IN(selectedCases)
Doesn't look right. The two operators (IS Null) and (IN (selected Cases) are run on. I would expact an "AND [field] IN (selectedCases)
You might also want some additional parentheses to clear up the precedence:
silvionr wrote: SELECT [Primary Number] FROM [Vital Stats] ( WHERE [Title-D] IS NULL OR [First Name-D] IS NULL OR
[Last Name-D] IS NULL OR [Inform Title] IS NULL OR [Inform first Name] IS NULL OR
[Inform Last Name] IS NULL OR [Address-infor-1] IS NULL OR [City/town-infor] IS NULL OR
[State-infor] IS NULL OR [ZipCode-infor] IS NULL OR [Inf RevRel] IS NULL OR [Director Name] IS NULL ) ???? [????] IN(selectedCases)
|
|
|
|
|
MSAccess syntax is: ISNULL() - there is no space between IS and NULL, and you need parenthesis.
Also, see what Rob Graham said about your IN clause.
--EricDV Sig---------
Some problems are so complex that you have to be highly intelligent and well informed just to be undecided about them.
- Laurence J. Peters
|
|
|
|
|
Hi all,
I see (almost) everywhere that the disconnected model for database access is fabulous. Granted, this is the easiest way in VS 2005 to build an application. And for shure, there are fine things in there, but I have doubt about a few things:
- in a multi-user environment, user A starts the application, and while he browses records, user B changes some of them. Unless user A specifically refreshes the data, he does not see the updated data
- records are not updated as soon as a user moves to another record. Say a user have been adding records for the last 5 minutes and have not hit the SAVE button. Then a loss of power occurs: say goodbye to the changes
- how about transactions
Is it that there are things that I don't understand, or am I right in fearing this model ?
Thanks
Gilles Plante
|
|
|
|
|
Gilles Plante wrote: am I right in fearing this model
No these are all things that you need to account for while devoloping. Make use of time stamp columns often. Ultimatly the disconnected model is less stress on the SQL server. This topic has come up several times on the message board, search it for "disconnected database" and you will find long conversations about how to deal with some of the issues you brought up.
I'd love to help, but unfortunatley I have prior commitments monitoring the length of my grass. :Andrew Bleakley:
|
|
|
|
|
hi every one,
i'm using mixed mode as an authentication mode, the problem that anyone can log in to the database server, please help...
Ala'a Al Atrash
Special Systems Co.
Culture St. - Amman - Jordan
Software Developer
Work Tel:- +962 6 5664221 Ext. 140
Home Tel:- +962 6 4752702
Mobile Tel:- +962 7 96700423
|
|
|
|
|
Ala`a Al Atrash wrote: i'm using mixed mode as an authentication mode, the problem that anyone can log in to the database server, please help...
In that case either you have given everyone the ability to log in via windows authenticaion, or the user name and passwords are out in the open.
A user cannot log into the database unless they supply the credentials to SQL Server that they have permission to log in.
If the user names and passwords are not in the open, perhaps you should review the logins to see who actually has access.
|
|
|
|
|
i wanna ask about the ability to connect sql server 2000 database files
without installing sqlserver 2000 itself but i'm hearin about MS desktop engine can give me this ability with coding using my application is this true or not?
|
|
|
|
|
malaky wrote: i wanna ask about the ability to connect sql server 2000 database files
without installing sqlserver 2000
You cannot.
malaky wrote: i'm hearin about MS desktop engine can give me this ability with coding using my application is this true or not?
If you install MSDE then you can attach your SQL Server 2000 database files (so long as they fit the restrictions of MSDE) and then connect to MSDE. NOTE: MSDE is the desktop edition of the SQL Server 2000 database engine - so you are still installing the engine in order to connect to the database.
|
|
|
|
|
Quote:If you are still not convinced then perhaps there is another reason you should look at migrating. Microsoft is working hard to help customers achieve the highest levels of security. As part of this push we have made the decision to not support MSDE on Windows Vista as we believe the combination of SQL Server 2005 Express and Vista is a better choice.
For further details click here[^]
"The key, the whole key, and nothing but the key, so help me Codd"
|
|
|
|
|
Jerry,
Thanks for the info.
Paul
|
|
|
|
|
Hi guys,
I'm writing a program for the high school where I work, I'm using VB 6 for the interface and MS SQL Server 2000 for the Database server. The thing is our school which belongs to a foundation (which also holds a consultant company) has two different network, the first is 192.168.212.* and the second is 192.168.3.*. I do the programming on the 192.168.212.* network and can access the server just fine if it were also installed with the 192.168.212.* IP number, can you guys please help me as to how can I make my program able to access the server if it were installed on the 192.168.3.* network. Any help would be much appreciated.
twindragons
|
|
|
|
|
Hello,
I am not much of a networking guy and I've had the luxury of not dealing with subnets, but I'll give it a try :->
I have a few questions. Who is on 192.168.212.* the school or the consulting company? Have you tried using the computer's network name instead of the IP?
Paul
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
