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[java] Writing to a Database

Started by Swattkidd Jun 16, 2007 at 7:22 PM 8 replies 1.2k views

Original Post

Jun 16, 2007 at 7:22 PM

Ok well i have a table that i want to send some information. I figured out how to read information from the table and i do know how to send information to the table, but the problem comes in when i want to getText from a textfield and then send that text to the table. to just send the text to the table i do this

    Statement sm = con.createStatement();
       sm.executeUpdate("INSERT INTO data "+"VALUES('person', 70)");

but instead of having 'person' i want it to get text from a text area and send that.

CaptainJester

101

CaptainJester

Jun 16, 2007 at 9:44 PM

Statement sm = con.createStatement();       sm.executeUpdate("INSERT INTO data "+"VALUES('" + myTextField.getText() + "', 70)");

Although this isn't secure. Once you learn some more, learn how to use prepared statements. That will increase your security.

Swattkidd

Author

Swattkidd

Jun 16, 2007 at 10:54 PM

ahh yes, i figured it out after a couple of hours :D

but yea i ran into another problem, how can i deploy my application, using a jar file, and still have it connect to a database?

because right now when i run my jar file it doesnt connect.:O

CaptainJester

101

CaptainJester

Jun 18, 2007 at 7:33 AM

How are you connecting now?

ROBERTREAD1

Jun 18, 2007 at 7:41 AM

This function is in VBScript but I'd recommend something similar in Java.

Function SQLString(sText, iLeft)
If iLeft=0 Then
SQLString = Replace(sText, "'" , "''")
Else
SQLString = Replace(Left(Trim(sText), iLeft), "'" , "''")
End If
End Function

It escapes ' chars to '' so SQL injection is harder and also trims text to fit into the width you set for the field

Swattkidd

Author

Swattkidd

Jun 18, 2007 at 10:16 PM

Quote:
Original post by CaptainJester
How are you connecting now?

Well see at first i realized i was connecting to localhost so i changed it to this

con = DriverManager.getConnection(jdbc:mysql://localhost:3306/java,
"meow", "meow

then i tried that same thing with my static ip, not localhost. Still no connection, i either get can not connect im guessing that is because of the port number or i get a NESTED exception which i have no idea why.

ddyer

Jun 20, 2007 at 6:31 PM

Quote:
Original post by Swattkidd
ahh yes, i figured it out after a couple of hours :D

but yea i ran into another problem, how can i deploy my application, using a jar file, and still have it connect to a database?

because right now when i run my jar file it doesnt connect.:O

Even if it's possible, this isn't a good idea. A database which
can be manipulated directly by a remote process (especially a java
process) can easily be hijacked and hacked.

Instead, implement the database manipulation by a trusted agent,
and communicate with the agent from your java process. Note;
your efforts will be wasted if the communication protocols
are tantamount to the java process writing the queries and passing
them to the trusted agent.

Swattkidd

Author

Swattkidd

Jun 21, 2007 at 3:35 AM

Well i will never really hand this application out, its just for me and my friend thats it. I am still having the problem of connecting to database from a JAR file. See above ^.

ddyer

Jun 21, 2007 at 11:12 AM

Unsigned applets can only open sockets back to the host from which
the applet was loaded, so the URL you use to open the
database needs to be similar to the code= url that
loaded the applet.

Swattkidd

Author

Swattkidd

Jun 21, 2007 at 5:20 PM

It is not an applet, its a normal application...

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