to get callerid through jdbc

[preethi Ayyappan]

Hi, i need to do this:i had initialized an extension number in the string Caller.I had a table dnc having fields name and callerid.i have to check whether the caller i have initialised is equal to any of the caller id in that table.if the caller is in the database, i have to display a message "dont call this number".if the caller is not in the database i have to display the number.since it is very easy, i am not getting the output.my code follows:please help me where i am wrong.

import java.sql.*;
   public class Connect
   {
      public static void main (String[] args)
       {
String Caller="5103";
Statement st;
        ResultSet rs=null;
           Connection conn = null;
           try
           {
                   Class.forName ("com.mysql.jdbc.Driver").newInstance ();
               conn = DriverManager.getConnection ("jdbc:mysql://192.168.1.5:3306/test", "dialer", "1234");
              st = conn.createStatement();
   rs = st.executeQuery("select * from dnc where callerid='"+Caller+"'");
while(rs.next())
{
String callerid=rs.getString("callerid");
if (Caller.equals("callerid"))
 { 
System.out.println("Dont call this number");                                   
}
else
{
String a=Caller; 
System.out.println(a);
}
 
} } catch (Exception e)
           {
               e.printStackTrace();
           }
          
   }}
    

.
It is displaying the output as 5103.where i am wrong.

Thanks.

[Paul Sturrock]

Your logic looks wrong. Your output code will only run if something is returned from this SQL:

select * from dnc where callerid='"+Caller+"'

so you'll only see something if there are records wit hthis callerid.

[preethi Ayyappan]

so,what should i do exactly?

[preethi Ayyappan]

please help me to correct my query

[Paul Sturrock]

Sorry, misread your problem.

Caller.equals("callerid")

This is an test to check whether the value of Caller* equals the literal string "callerid", rather than the value of the variable callerid. Remove the quotes.



(* BTW, in Java the convention is to define variable names that start with a lowercase letter. This avoids confusion between variable names and types)

[preethi Ayyappan]

thanks.I've tried that too.Now i am getting the output "Dont call this number".But if i change the Caller number to a number which is not in my database,it should display that number.But it displays nothing.what is the wrong in my code.Why it is not taking the else part?

[preethi Ayyappan]

If i hardcode any number which is inside my database in the query like this

select * from dnc where callerid="5101"

.
I am getting output for if part as DOnt call this number,if the String Caller="5103";
even if changed the String caller="5110"which is not in the database,it displays the same number 5110 as i have mentioned in the else part. but I dont know why i am not getting the output for else part when my query is like this:
select * from dnc where callerid='"+Caller+"'.

please help to do this simple program

[Paul Sturrock]

Originally posted by preethi Ayyappan:
thanks.I've tried that too.Now i am getting the output "Dont call this number".But if i change the Caller number to a number which is not in my database,it should display that number.But it displays nothing.what is the wrong in my code.Why it is not taking the else part?

See my earlier post. Your logic means your output will only happen if a record with the defined callerid exists.

[preethi Ayyappan]

Where i have to modify my code to get the proper outputs which i need?
Where i am wrong?

[Paul Sturrock]

You have a conditional check, where you tests the equality of Caller with what is returned by your query. This is a pointless check, since you know this is equal if your query returned something. This check is done inside the while loop you are using to navigate through your ResultSet. So if your query returns no results (as it will if a record with your callerid does not exist) this code will not be run. This check needs to be changed so it is run if your ResultSet is empty.

[preethi Ayyappan]

Then how should i check the condition.please guide me

[preethi Ayyappan]

if (Caller.equals(callerid))

.In the place of callerid,what should i give.could you show me in code?

[Paul Sturrock]

The psedo-code would be something like:

Connect to database 
Run SQL 
 
If ResultSet has entries 
    output "don't call this number"
else 
    output Caller value
 
close ResultSet
close Connection

So what you need to do is work out a way of flagging that the ResultSet was empty. Perhaps you could use a boolean, set to true if the ResultSet had any entires?

[preethi Ayyappan]

Hi
Thank you for your help.I got the result.