inserting dialogbox within condition in android

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SQL-Server

Mobile

Android

dialog

I created an apps which insert data to sql server.there is no problem in connecting to the server . but i want to use a dialog box when user enters same data which already been inserted to database .but i don't know why it is not working...
my code is here.....

public void insert(){
       final String fname=name.getText().toString();
       final String fcity=city.getText().toString();
       ResultSet rs;
	 	 try{
	        	 Statement statement1=connect.createStatement();
	        	 rs=statement1.executeQuery("SELECT * FROM FORM1");
	        	 List<Map<string,string>>data1=null;
	        	 data1=new ArrayList<Map<string,string>>();
	        	 while(rs.next()){
	        	 Map<string,string>datanum1=new HashMap<string,string>();
	        		 datanum1.put("a", rs.getString("NAME"));
	        		 datanum1.put("b", rs.getString("CITY"));
	        		 data1.add(datanum1);
	        	 }
	        	 if(data1.contains(fname)!=false){
	        		 AlertDialog.Builder adb=new AlertDialog.Builder(context);
	       		 adb.setTitle("My Records");
	      	 adb.setMessage(fname+" Already exist... do u want to overwrite???");
	        		 adb.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
	@Override
         public void onClick(DialogInterface dialog, int which) {
	// TODO Auto-generated method stub
	try{
	 Statement statement2=connect.createStatement();
	statement2.executeUpdate("UPDATE FORM1 SET NAME='"+fname+"',CITY='"+fcity+"' WHERE NAME='fname'");
	}catch(Exception e){
	Log.e("ERROR", e.getMessage());
	}
							
	}
	});
	adb.setNegativeButton("No", new DialogInterface.OnClickListener() {
						
	@Override
	public void onClick(DialogInterface dialog, int which) {
	// TODO Auto-generated method stub
					
	}
	});
	AlertDialog adbc=adb.create();
	adbc.show();
	}
	else{
	Statement statement3=connect.createStatement();
	statement3.executeUpdate("INSERT INTO FORM1(NAME,CITY) VALUES('"+name.getText().toString()+"','"+city.getText().toString()+"')");
	}
     	}catch(Exception e){
        Log.e("ERROR", e.getMessage()); 
	}
}

if any one plzz tell me what code should i use