First point I suggest is read the
Read-Me thread which is the first thread in the JSP forum, You are performing database operations from directly withing your JSP page which is considered a bad practice, the above thread will guide you on how to go about organizing your code nicely so that when you get on real world projects in JSP you will be thorough with the right practice.
Now let us check how your coding is going on. First thing I see is you are failing to consider all the circumstances and you have just not traced mentally how your
if and
else if statements will be executed.
for ex consider this :-
if(user == null || user.equals(""))
{
response.sendRedirect("register.jsp?err = please fill the username");
}
else if (user != null)
{
query = "select username from msUser where username like '%"+user+"%'";
}
In the "if" condition you are already checking wheteher
user == null or blank
user.equals("") so why do you need to check again in the
else if (user != null) , the code in that else if block could been easily put in the
else block.
Now just take a look at your query:-
SELECT username
FROM msUser
WHERE username LIKE '%"+user+"%'
This would list all the users to you which contain the current user's username.
For example if the current user wants to register the user name as "dracula" and if a user called "dracula1" already exists then the above select query would give you the details of user "dracula1" and hence your system would not allow the user "dracula" to be created even if no such user exists.
Your query should have been:-
SELECT password
FROM msUser
WHERE user='"+user+"';
Now we may have corrected the query, but you have not fired the query in the database to check if the user exists !!!
Also why are you checking if
user == query , there is everything wrong in that also.
First thing is that when you want to compare two strings you do not use the
== operator, you use the
equals() or
equalsIgnoreCase() method of the
String class.
Also if your consider this logically it is absolutely incorrect. What is the use of comparing the
According to me you still do not have any firm foundation of the language so I suggest you first get your basics of Java strong, by going through tutorials mentioned in
this thread.
Next go through the
JDBC tutorial, note in core Java only and once you have established yourself firmly in Java only then jump to JSP (else you will just find yourself coming back time and again to clear your core java concepts).
Also you need to read a little background information about JSPs cause you seem to be confused as to what is meant by JSP 2.0 standard etc. Any book on JSP worth its salt will cover these basic topics in the first or second chapter itself.
BTW its
Manchester United and not Manchaster, if your are going to use the name of my favourite, you better spell it correctly !!!
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