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I have a table in my DB containing a column of type Datetime, which allows null values. I created DataSet on which I drag&droped this table. Everything was fine, DataTable with TableAdapter have been successfully created and are both working. When I select this column in this DataTable (on designer surface) it shows in properties that this column is indeed nullable (AllowDBNull: True).
However ADO.NET generated false code for this example. Look at the following code:
var t= new ABCTableAdapter().GetData();<br />
ticket[0].MyNullableColumn -> this return 'Datetime' instead of 'Datetime?'.
If a given record in DB has indeed null value in this column, then such code generates "StrongTypingException". So this is quite clear that ADO.NET made some mistakes in code generation.
I tried deleting all DataSet and recreating it from scratch. Also I`m sure that my column really allows null values as some records have such value in this column.
Could you please help me and tell how am I supposed to force ADO.NET to generate this code properly? I want the following code to compile:
if (t[0].MyNullableColumn != DBNull.Value) {...}
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This is why you don't use the drag and drop crap.
It generates a method .IsMyNullableColunNull()
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Jamie is right, learn to use a proper DAL and get control of your application, don't rely on MS generated code!
This may be a better option for you
t[0].MyNullableColumn ?? DBNull.Value
Never underestimate the power of human stupidity
RAH
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Sure sure, its the best to write everything in assembler or even machine code. Such approach is senseless. ADO's designer saved me a lot of time during many years, this is first time it fails. Still a very good result.
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Yoyosch wrote: Sure sure, its the best to write everything in assembler or even machine code.
Actually thats a bloody silly statement, I'm talking about the framework you use every day.
Yoyosch wrote: ADO's designer saved me a lot of time during many years, this is first time it fails
This would seem to indicate that you are doing fairly straight forward CRUD operations. We see this type of problem in the forums regularly, and yes it is generally something slightly different.
IMHO it is not the productive issues, the designer/wizard stuff does make it quick and simple, it is the lack of any deep knowledge about your data and tools.
Never underestimate the power of human stupidity
RAH
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I implementd CLR stored procedure on 'Database1'. I would like to perform some UPDATE statements inside this CLR stored procedure in 'Database2'. Is is possible? If so, then how?
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You can have a use database statement in your proc.
I have not idea how you do that in the clr, I have never turned it on, I use TSQL. You will find there are very few devs use the clr, most will use TSQL and sql servers SSMS tool. You do not need another layer of abstraction between you and your data.
Never underestimate the power of human stupidity
RAH
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Is there any chance I make the SQL server think Sunday is the last day of the week (not the first day of the next week) with out changing the regional settings?
This is messing up the weekly reports queries...
I have no smart signature yet...
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Solved my own problem!
SET DATEFIRST 1; -- set's the first day of the week to monday
SET DATEFIRST 7; -- set's the first day of the week to sunday
I have no smart signature yet...
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Hi All,
I have a SQL database column, name "Closing Date" with datatype as Datetime. For example, the entries are like this:
1-Nov-2009
21-Dec-2009
10-Jan-2010
21-Mar-2010
11-Apr-2010
Now What I want is to select a date which is less than my requested date from a text box.
e.g. If I want to select a date which is less that 31-Mar-2010, then I should get 21-Mar-2010.
or, If I want to select a date which is less that 9-Jan-2010, then I should get 21-Dec-2009.
Presently I am using following in VB.net.
cmd = New SqlCommand("SELECT [Closing Date] FROM client_details WHERE [Closing Date] <= textbox.text", con)
But I think I need to use something else. Hope My query is clear. Please suggest me how to go ahead?
Regards
R.S.
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Try
cmd = New SqlCommand("SELECT [Closing Date] FROM client_details WHERE [Closing Date] <= @selectedDate", con);
Dim param As New SqlParameter("selectedDate", DateTime.Parse(textbox.Text, CultureInfo.InvariantCulture));
cmd.Parameters.Add(param);
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Hi,
try
"SELECT MAX([Closing Date]) FROM client_details WHERE [Closing Date] <= '"+textbox.text+"'"
(assuming C# is what you need). With some comments:
1. it is much easier when database field names don't contain special characters and spaces.
2. such SQL statement is vulnerable to SQL injection: users could enter parts of an SQL command, which your code then executes. Solution: verify the textbox content, or better yet, use SQLparameter.
3. the user must enter a string representing a date, according to the format your database is expecting. It is better to have the user enter data according to the system's regional settings, then to convert it to what the database needs. Again SQLParameter is the better approach: use DateTime.Parse(textbox.text) (or TryParse), then set the SQLParameter.
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Here is another alternative - no better, no worse just different.
"SELECT TOP 1 [Closing Date]) FROM client_details
WHERE [Closing Date] <= '"+textbox.text+"'
order by [Closing Date] DESC"
As Luc suggested use parameterized queries - this is IMPORTANT.
There are usually a number of ways to sole a problem, try both and look at the execution plans to decide the better solution. Then throw an index on the close date field and see the difference!
Never underestimate the power of human stupidity
RAH
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This is for SQL Server 2008:
Will the stored procedure be rolled back if the db server gets an error (server crash or performance problem) in the middle of it's operation?
This is the idea:
- stored proc spTest contains 2 insert statements
- exec spTest
- spTest executes 1st insert statement
- stored procedure still running... but server gets some problem that's unrelated to this stored procedure, which causes the stored proc to stop (e.g. server crash)
Will the data in the 1st insert statement be rolled back?
Thanks in advance!
Rafferty
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What do you mean?
Currently, these 2 insert statements are not enclosed in try catch blocks, but I didn't think that I need to because the error is caused by something else that is external to this stored procedure.
Or is there some DB configuration-wide that I should set?
Rafferty
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Rafferty Uy wrote: Will the data in the 1st insert statement be rolled back?
How about wrapping them both in a single transaction[^].
I are Troll 
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Hi Eddy, thanks for answering. I understand that it's better to wrap both in a single transaction.
My question is really what happens if i don't. I want to know the normal behavior of sql server in such a case, not how I can improve the code.
I'm investigating a bug and I suspect that this was the cause of the problem... but it seems far fetched because the server didn't crash... it just experienced some performance issues.
Thanks again!
Rafferty
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Rafferty Uy wrote: My question is really what happens if i don't.
It will write up to the point of the crash, and execution will halt. No automatic recovery,
If it crashes midway, the first sproc might be saved, the second might not. If it crashes during a write-operation, your entire database might become corrupt.
I are Troll
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Just the answer I'm looking for! Thanks a lot Eddy! This really helped
Rafferty
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hello folks,
I got headache to figure out SSIS SQL 2005 error when windows task scheduler is triggered...
I setup the batch file like below to run it every morning,
"C:\Program Files\Microsoft SQL Server\90\DTS\Binn\DTExec.exe" /f c:\BAT\SSIS\DATATRAN.dtsx >> c:\BAT\LOG\DATATRAN.log"
it had been working until last month, now I can run this batch file without any problem manually and no problem to run the scheduled task manually, but it shows errors when run the scheduled task every morning... SSIS is stuck in the process 43% completed,
Is there anyone can give me tips?
thanks!!
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MARS (Multiple Active Results Sets), which simplifies the application design process
ALTER rename process for symmetry in renaming databases
Application and Multi-server management for Data-tier Applications which further streamlines application design and enables deployments of database applications directly from SQL Server 2008 R2 and Visual Studio 2010 to SQL Azure for database deployment flexibility
Details in the Blog Post http://blogs.msdn.com/sqlazure/archive/2010/04/16/9997517.aspx
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Vista/64
VS2008
I'm to add a SQL Server database object to my project, but when I try, I get this error message:
Connecting to sql server files (*.mdf) require sql server express 2005 to function properly.
Well, it is installed, and when I run express manager studio, everything seems to be fine. I can also create connections in the server explorer in vsiual studio. When I googled the error, there was exactly one hit that I can't browse top (because of the restrictions on our network).
.45 ACP - because shooting twice is just silly
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"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
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"The staggering layers of obscenity in your statement make it a work of art on so many levels." - J. Jystad, 2001
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Can you post either the link you can't get to or the exact search phrase in case someone CAN get to it and then render help?
Tim
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