Sql database connection in C#

Question

0.00/5 (No votes)

See more:

SQL Database connection in C#.net

What I have tried:

C#

string str;
   SqlConnection cnn;
   str = @"server=(local);database=SMS_Data;Integrated Security=SSPI";
   SqlConnection cnn = new SqlConnection(connetionString);

Posted 27-Sep-18 21:38pm

Ashutosh_jha

Updated 27-Sep-18 22:32pm

Maciej Los

v2

Add a Solution

Comments

Eric Lynch 28-Sep-18 8:00am

If you've tried the above, something must have gone wrong. Otherwise, you wouldn't be here asking questions :)

Generally, in C#, if "something goes wrong" an exception is thrown and (unless you handle the exception) it is displayed somewhere. If you really want help, you'll need to share the details of that exception.

There are a bunch of different things that can "go wrong". Some examples include: you (as a user) are not authorized to access the database, you've provided an incorrect database name, SQL server is not running, the connection is blocked by a firewall or other network setting, some problem has caused a timeout before the connection is completed, or many, many other possible issues.

To help you, we need to know which of these many possible issues is the cause. The exception usually provides enough detail to (at a minimum) restrict the number of possibilities. Once we know what issues might be possible, we might be able to provide some advice about how to fix that specific issue (or issues).

Without that information, all we can do is guess, which is both a waste of our time and unlikely to help you.

Of course, this all assumes your code actually compiles. As others note, the variable "connetionString" is undefined, so either the compilation should fail or your question does not include the code you actually tried (perhaps a typo?).

As a secondary issue, OriginalGriff is correct, you shouldn't hard-code connection strings in the source code. Generally, I usually save these in either the application or web configuration file. If you also add the type of application you are writing (Web or WinForm/WPF/Console) into your question, you might get more specific information about how this is done.

Hopefully, you'll add enough information, to your question. help us to help you. Good luck.

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Answer 1 · 2018-09-27T21:50:00

Solution 1

Um. Look at your code:

string str;
SqlConnection cnn;
str = @"server=(local);database=SMS_Data;Integrated Security=SSPI";
SqlConnection cnn = new SqlConnection(connetionString);

What is in connetionString? Because the variable you put your actual string into is called str ...

You shouldn't "hard code" connection strings: it means you app has to be changed to switch between dev and production if nothing else, and that's dangerous. It also leads to loads of different places to change when you do release the product. Use a config file or similar instead. This is how I do it (but it's probably overkill for you): Instance Storage - A Simple Way to Share Configuration Data among Applications[^]

Posted 27-Sep-18 21:50pm

OriginalGriff

Comments

Ashutosh_jha 28-Sep-18 3:53am

string str;
SqlConnection cnn;
str = @"server=(local);database=SMS_Data;Integrated Security=SSPI";
SqlConnection cnn = new SqlConnection(str);

OriginalGriff 28-Sep-18 4:06am

Better - but seriously, don't use hard coded connection strings.

Ashutosh_jha 28-Sep-18 4:20am

give me correct way and code

OriginalGriff 28-Sep-18 4:28am

You are going to have to explain yourself rather more, I'm afraid: we have no idea what is wrong. Any error messages, what does it do that you didn't expect, or not do that you did - that sort of thing.

Ashutosh_jha 28-Sep-18 4:40am

I am trying to make a simple windows application in visual studio 2005 with sql server 2008. i have no any idea how to connect with database via code.

OriginalGriff 28-Sep-18 4:54am

What part of it do you know how to do?
I'm not trying to be funny or annoying: we have no idea what you have tried, where you are stuck, or what help you need.

Remember that we can't see your screen, access your HDD, or read your mind - we only get exactly what you type to work with.
So explain in detail and we'll try to help. But typing the least you can get away with and hoping isn't going to do it - the better the info you give us, the better the help we can give you!

Maciej Los · Answer 2 · 2018-09-27T22:33:00

You didn't provide enough information about your issue. Nevertheless...

First of all, i agree with OriginalGriff, because:

Quote:
Embedding connection strings in your application's code can lead to security vulnerabilities and maintenance problems. Unencrypted connection strings compiled into an application's source code can be viewed using the Ildasm.exe (IL Disassembler) tool. Moreover, if the connection string ever changes, your application must be recompiled. For these reasons, we recommend storing connection strings in an application configuration file.

See: Connection Strings and Configuration Files | Microsoft Docs[^]

For further details, please see:
Connection String Syntax | Microsoft Docs[^]
SQL Server Connection Strings for ASP.NET Web Applications | Microsoft Docs[^]
SQL Server connection strings - ConnectionStrings.com[^]