There is a lot of tutorials out there showing me how to create a new table and ammend the data. But will creating a new table every time overwrite my existing table?
Once the table has been created and the rows of data have been added, I wouldn't need my program to create a new table again. Just read and ammend from it.
I don't want the user to create a table, so I just want the table to already be there before I even run my program.
I figured I could use run something like this to create my database tables once:
https://www.tutorialspoint.com/jdbc/jdbc-create-database.htm
Run it! And then once it is created, use this next guide to connect to where I stored it in the actual program.
https://www.tutorialspoint.com/jdbc/jdbc-select-database.htm
Be nice to find a tutorial on how to just manually make the database parameters outside of code.
The project is for university, they want me to create a client similar to MySpace. Have clients connect to a server, share music and message friends. I have done the UI and multi threaded server connections and understand how to read and write data to the UI or File. Just figured an SQL database would be the best way to store all this user data.
You just need to check the table Exist or not.
If the table exist then use it else create it and then you can use it.
Related
[So as you can see in the picture, i'm a newbie in android programming and i just had an assignment concerning creating a management system app for university.
The views you see in the picture are just customly made with xml(Table layout) and the data are just dummy data placed on the respective textviews in the tables. I desire to create a database for students and all those data e.g names, gender, should be fetched from the database or sent. Remember, as for courses the number of courses would differ from one degree prog to another(imagine a student with less ormore courses than the tables i sampled there).
How do i acomplish this
As for database, im thinking of using SQLite or Firebase ]1
There are many ways to approach this, depending on the requirements of your program. If you need to share data between multiple people or devices, you probably want a database that lives on a web server, and you would write an API (application programming interface) which you would call from your app, and it would go and get the data from the database and return it to your app.
If your app is meant to be 'stand alone', where you could use it without being connected to the internet, then yes, a SQLite database is a good solution and it is pretty easy to integrate into your app.
To create a SQLite database, you can download the free tool SQLiteStudio. Once you create the database (usually saved with a .db file extension) you can add it to your project in the Assets folder (create it if it doesn't exist). The folder lives at the same level as the bin and gen folders in your project.
Next, search for a class called DatabaseHelper.java, it has a number of methods for opening, closing and querying a SQLite database, copy that to your project.
At the start of your program, you should check to see if you have a copy of the database in your local data/databases folder in your App's file storage area. If you don't have a copy there, which on the first execution of your program, it will not be there, then you have to copy the database .db file from your Assets folder to the data/databases folder, then open it there. If it is found, you've already done this, so, just open it.
When you want to read data into your app, you execute a SELECT statement to retrieve data from your database into a Cursor object, and return that cursor from your DatabaseHelper class to your activity. In your activity, you will iterate through the Cursor, reading one row at a time, and copy the data into program variables. Sometimes, you will create a class object to hold one record, with attributes that match a row from your query, and you'll create an instance of your class, fill it with the data from the Cursor, then add that object to an Array List of objects which your program can use at a later time, say, to display a list of people or whatever it is you queried for. Once the Cursor has been read to the end, you close the Database by calling a close method in the DatabaseHelper class.
That's the general idea. If you search for a copy of the DatabaseHelper.java class, that will get you started. Then, search for some example projects that use that DatabaseHelper.java class so you can figure out how to use it.
Good luck!!
My app connects with diferent databases. First of all, I generate the orm code with speedment for the first database. But when I try to connect to a newone Speedment deletes the code generated for the previous one.
The Speedment Tool can't currently connect to more than one database, but there is a hack to get around this.
Speedment will generate code based on the speedment.json-file. When you connect to a new database, your speedment.json-file is overwritten and is therefore not used in the second pass. To get around this, save the original file as something else (like speedment2.json) and then connect to the second database. Instead of generating, simply press "Save". This will create a new speedment.json-file without generating code. Then open the created file in a text editor and add manually combine the files. Look for an value with the key "dbmses". It should be mapped to a list of objects, in the first file the object represents the first database and in the second file it represents the second database. If you combine these two lists, save the file and then reopen the UI, then you should see both the databases there. From here on you can use the tool to make changes and regenerate code as usual.
I am developing a small app for hotels. I am using java and mysql. I use mysql to save booking information and guest data and so on.
But now I want to make my program to be more flexible.
For example if I want to add more apartments(store apartment names) or change the payment methods. At this time I store the data as binary in files and read them from there when I start the program or when I need them.
Is this method correct? or is a better way? Should I use the mysql and read the data from there?
You should use a mySQL database. Store the data in tables with different columns based on the info. Use the tables to store the information so you don't need to convert it to binary.
To talk to the table, use the JDBC. There is a nice tutoral on using JDBC with mySQL. Refer to the SQL website on setting up tables on your mySQL database.
I am using JDBC to connect to a mySQL database in my program. During runtime, the user can modify the contents of the database by adding new ones (more functionality is coming but right now that's all I have). However, when a new entry into the database is created I want the gui that is displaying the content to update themselves with the modified data.
I know how to update the gui elements, but that doesn't seem to apply to the ResultSet created from my database.
I am quite new to mySQL and JDBC so any help would be very appreciated !
First questions:
- If it is a web application, you can use Ajax and ajax callback to manage return of your application (success or failure)
- If it is a standard application, you can manage in that way (which work from my side):
As soon as user added data, you needs to wait the result of your database. If (insert/update/delete) does not return any exception, you have to modify your GUI (add/update/remove) your display. If you have any issue you should not modify your gui.
Do not perform any select all, as you can crash your application in case of huge db.
I have a database with tables in it which contains information. I would like to retrieve data from the table which is on the database to the table which I have made on a GUI form. I have tried retrieving the data using system.out.print method and I get results, meaning the database connection works and recognizes the table. Only problem is I do not know how to that for tables in the code. Please keep in mind that the GUI I made, the code was generated automatically so I do not have 100% access to the code.
Your connection to the database seems to be correct, however, you cannot set your table to contain the values you need. If the diagnosis is correct, then below you will find useful information:
I do not know what are you using for tables, I will assume you are using JTable, but if you use something else, only technical details should change as the thought process should remain intact.
To get general knowledge, please read this tutorial.