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Closed 11 years ago.
as the topic header shows my question is about Coding an online chess by VB.net.
I coded the chess game with all rules , now I designed a login form for it, but I don't know how to connect to a Database and send query , to check the User and pass.
I searched about connecting to a DB and I found something. but i didn't found anything about sending query.
I need a code that contains connecting to a DB and sending query for example about checking username and password to DB.
thanks.
Well, the simplest answer is to use what's called ADO.NET. It's basically a set of classes within the .NET Framework which are used to access a database. Depending on the database you use, there may be a built-in driver (MS SQL, Access, etc.) or you may need to use a 3rd party one (MySQL, PostgreSQL, etc.).
Here are a couple of examples. There are many more.
You can also use LINQ to SQL, which internally uses ADO.NET but presents the data access to the developer is a more fluent way. Or take it another step and use Entity Framework. Etc.
Essentially the question itself is very broad. There are a number of ways you can access a database. But these are the places to get started. If/When you run into specific issues with code not working the way you expect, we'll be happy to help.
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It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.
Closed 10 years ago.
Needed some advice as i am writing my first iOS application,
1. what is the best way(simplest) to link an app to a database and does the database have to be SQLite (the databse will be external ie. linked via the internet)? i have used mySQL before in MAMP,
I have read up on other post and they suggest complicated methods like via JSON etc, please provide a simple way and a book/guide/web site that could teach me your suggested method would be much appreciated too :)
SQLite is one of them.
However if your requirement is to share the database, you can go with mySQL or even Oracle etc.
JSON, xml are the tools that will help you to make a client server application.
Useful link:
http://jainmarket.blogspot.in/2009/05/iphone-sdk-tutorial-reading-data-from.html
SQLite is generally used for a local database (aka, on the device itself) through CoreData. But it seems like you have a remote MySQL database you want to connect to.
You should build some API that your iOS app talks to to get data from a database. Typically this is done over http which generates JSON in whatever server language of your choice (eg - python, ruby, php, etc).
For the iOS side, you'll probably use Apple's builtin features: NSURLConnection and NSJSONSerialization.
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Closed 10 years ago.
I have an access DB, which is split into a Backend and Frontend, that has c.a 100000 records in 60 tables.
I have this idea, that I can switch my Backend to a MSSQL Server Express.
I would like to know if it is worth the effort to attempt this idea. And which advantage do I have if my Backend is SQL Express and Front End access.
Thank you for your ideas
Definitely worth swapping to a version of SQL Server or MySQL. It can take a while to get the hang of once you have migrated from Access but using MS Sql Server will allow you to import tables easily and you'll have a more future proof application. Worked well for us
It depends on how many users are concurrently using your database and if your backend is located on a LAN or is a local database.
The number of records (100000) are not so much for Access to handle.
If your database is on a LAN location or if you have concurrent users, you should get some advantages moving to SqlServer, but some plumbing and rechecking of your code will be required.
Remember, Access is fast and easy to build application with, but, at its core, is a personal database adapted to work for low concurrency situations. Sometime (and I tend to blame the programmer instead of Access itself) it is not suitable for concurrency use. If your application is critical then, as with every database solution, a good disaster recovery plan and quick maintenance intervention time are mandatory.
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Closed 10 years ago.
I find that creating SQL tables tedious when starting to create a web app (ASP/Python/PHP).
Do you guys know any tools that makes creating tables quicker and faster and easier? Thanks in advance! :-)
In my opinion writing a CREATE TABLE statement is far less tedious than writing HTML pages.
The recommended approach is to use a ER design tool co create and define your database model. Most (if not all) ER designer can then create the necessary DDL statement directly from the model.
With this approach you also have a documentation of your database model which is always a good thing.
It depends on the tools/libraries you use to create your app.
If you use an ORM, many ORMs offer you the possibility to create the database with all tables automatically, according to the classes and mappings you defined in your application.
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Closed 10 years ago.
How can I retrieve data from a SQL Server using LINQ and display each tuple in a table in the UI?
I would also like to know how I can convert the data retrieved in to JSON and send it to clients who accessed that particular service.
Any help is highly appreciated.
How can I retrieve data from a SQL Server using LINQ? Add a data context (.dbml) to your project and link it to your SQL database, adding in all the tables. You use the MyDatabaseContext class to interface to the database and execute LINQ queries.
and display each tuple in a table in the UI? Create a GridView using a LinqDataSource with your new DataContext to pull in the appropriate data and display it.
convert the data retrieved in to JSON.. use something like the open-source JSON.Net library.
and send it to clients who accessed that particular service? Add a web service project to your solution (.wcf or .asmx), create an appropriate interface for the methods that should be called and implement them to return the correct data.
Note that at this phase in the project, you should be doing something called research, not asking questions. Google is a place to start. Come back when you have specific questions or implementation issues in trying to build your solution. What you've given us is a spec, not a question, and those do not belong here.
It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.
Closed 12 years ago.
I want to know about SQL injection.
So, please help me.
Lots of information about SQL Injection on wikipedia, and xkcd has a very good example as well.
In general, if your application is using a SQL database, a SQL Injection attack is an attempt to use your program to pass dangerous values to the SQL database.
The best preventative measures are to never construct SQL strings without cleaning them up - the best way to do this is to use parameterized queries and widely used data access libraries.
Start here: google "sql injection".
You will see that there is plenty to read about it.
If you want to protect yourself against sql injection, you have to be a bit more specific, as the exact methods differ depending on the database and on the platform using the database.
It is the technique to manipulate the input to control your sql. Read more here is better for you
Attacks by Example
Wiki
Couple of places to get started:
OWASP: Lots of principals on secure web app design. Check the first entry of the Top 10 on injection
Injection for .NET developers: Details on what it is and how to protect against it if you're working with .NET.
It allow a attacker to tamper with existing data, destroy the data or make it otherwise unavailable, and in short become administrators of the database server...
This attack involves injecting SQL commands in the query input thus effecting predefined SQL commands exection.