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You are executing a Sql command without assigning a connection to it. You can either include it in the constructor on the SqlCommand or you can add it explicitly through
command.Connection = ...
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Do i need to say:
command.Connection = new SqlConnection(@"Data Source=JOHN-PC\SQLEXPRESS;Initial Catalog=subiect1;Integrated Security=True");
or something like that?
I repeat, i am new with C#. If someone knows and is willing to answer my questions, i will be very grateful. If they don't have anything useful to say, they are asked to keep their opinions for themselves.
Thank you very much!
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I would tend to do something like this:
using (SqlConnection connection = new SqlConnection(... put connection details in here...)
{
command.Connection = connection;
command.ExecuteNonQuery();
}The reason you would do this is that the connection to the database is closed as soon as possible after you have finished with your query.
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Thanks, i solved the problem. It works now!
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On top of what Pete said, you don't need either of those IDENTITY_INSERT commands being executed. It appears you have no idea what they're for and are just copying and pasting code from the Internet without trying to understand what it does or why it's there.
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I am sorry i forgot to mention i am new with c#.
And i inserted those commands because i got the error IDENTITY_INSERT is set off. So, what should i understand from that error? I thought i needed them, but i didn't know where i they are needed.I repeat, I've just put them there because of the error i received. How can i know it is wrong what i have done since i am new with c#?
This is the purpose of my question, people, to tell me what is wrong, not to receive reproaches. If i was smart enough, i didn't ask questions in forums, i would have solved my problem alone.
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You're trying to insert an explicit value into an IDENTITY column[^]. The value of this column will normally be allocated by the database, which is why it gives you an error when you try to insert an explicit value.
In certain restricted cases, it is necessary to allow explicit values to be inserted into an identity column. This is the only time that IDENTITY_INSERT[^] is used. This should only be done as a maintenance operation, and not part of a normal insert.
If you want to insert explicit values into the column, then remove the identity property. Otherwise, don't specify the identity column in your INSERT statement.
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Thank you for clear explanation.
To learn all there is to know. I know I'll be disappointed one day, but I've made a good start, and the eventual disappointment is likely to be brief.
-Roger Wright
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Hello,
I need to encode a string to a 6 or 8 digits hash and decode it to original string. Encoded string has to include only numbers and alphabetic characters. Thanks.
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My understanding is that the whole point of a hash is that it cannot be decoded back to the original string - let's see if I am proven wrong on this.
“That which can be asserted without evidence, can be dismissed without evidence.”
― Christopher Hitchens
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It can be hash or something like that, I need to convert a 12 characters long string to 12 characters long string or smaller meaningless one. Thanks for your reply.
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In which case just use some sort of algorithm that is applied to the ascii value of the first character, then use the output from this together with the value of the second character to convert the second character and so on(this way it is a little bit harder to crack the sequence of characters).
To decode it all you need to do is reverse the process starting from the first character again.
“That which can be asserted without evidence, can be dismissed without evidence.”
― Christopher Hitchens
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Come on! You want to convert *any* string and reduce it to 6 or 8 digits, and then be able to convert it back again?
Well, if you find a way I'll be impressed. Not to mention that we'll be able to zip anything up in just 6 digits..!
Regards,
Rob Philpott.
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Rob Philpott wrote: we'll be able to zip anything up in just 6 digits..
That would be an incredible compression ratio if one could achieve that 
"I've seen more information on a frickin' sticky note!" - Dave Kreskowiak
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Maybe someone can help you when you explain What it is that are trying to achieve? Why do you need to generate the 'hash' and translate it back?
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I need to generate a meaningless code that includes last 4 characters of MAC address and a date for example; F28D31122014. Thanks.
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Creating a meaningless code is easy, but it is impossible to regenerate a MAC address from only the last 4 characters.
Still don't understand WHY. WHAT are you trying to accomplish?
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candogu wrote: I need to encode a string to a 6 or 8 digits hash and decode it to original string
That is not possible. And it is proven as well.
Now if you want to take a string or binary data and create another string which will only contain alphanumerics then that is fairly easy. In most cases the second string will be longer than the first. You can look to Base64 encoding to see an example of how you might do this. (Base64 is similar to but not exactly the same as what the output you are asking for is.)
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Hi, I have c# dll and I am using that dll in c++ with the help of COM Interop by importing the corresponding .tlb file in my .cpp file(#import "com.MyIntrop.tlb") and its working absolutely fine but now I want to use same dll in my C code but because I can not use #import in C how to use same dll which I have register as COM assembly in C.
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The .tlb file is typically created by the MIDL.exe from the .idl source file. It has an option to generate .c/.h file to be used by C programs. But since you did not create the .tlb file (I assume it was auto-created by a tool), I don't think you can do much about it.
Here's a workaround. I'm not sure if it will work. You can use OleView.exe to reverse engineer the .tlb to .idl and then use MIDL.exe to compile the .idl back to .tlb with the option to generate .c/.h files. You can then use these files in your C program.
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Another thing you can do is make a C++ DLL that wraps the C# DLL. You would then use the C++ DLL in your C code.
That is what I have done in the past, and it makes the type conversions a lot easier.
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Thanks for the reply. I tried this, I have creted c++ dll anr I have wrapped c# dll in c++ dll but I am not able to load that c++ dll in C code. I used "LoadLibrary" function to load the dll but it didn't work and do we need to have .h file to load c++ dll?
Thank You.
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Thanks for the reply. I will tell you why do I need to use c# dll in c, see we have already written code in c which we are going to use across platforms(Windows, windows phone, iphone, android) and from that code written in c we are going to call respective functions of respective platforms to achive Bluetooth communication. Now I have written code for Bluetooth communication in c#(dll) and I want to use it in already written C code. If there is any other way to achieve this apart from using c#(dll) in C code please let me know.
Thank You.
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