Update my naive sql.java

my naive sql.java

@@ -1,3 +1,4 @@
+import java.sql.PreparedStatement;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
@@ -11,6 +12,19 @@ protected void doGet(HttpServletRequest request, HttpServletResponse response) t
         try {
             Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/db");
             String user = request.getParameter("username");
+            String query = "SELECT * FROM users WHERE username = '?';";
+            PreparedStatement stmt = con.prepareStatement(query);
+
+            try {
+                stmt.setInt(1, Math.round(Float.parseFloat(request.getParameter("username"))));
+            } catch (NumberFormatException e) {
+                // MOBB: consider printing this message to logger: mobb-72204bd3d2910aa4632d5a5fedaadbec: Failed to convert input to type integer
+
+                // MOBB: using a default value for the SQL parameter in case the input is not convertible.
+                // This is important for preventing users from causing a denial of service to this application by throwing an exception here.
+                stmt.setInt(1, 0);
+            }
+            stmt.executeQuery();
         } catch (Exception e) {
             throw new ServletException(e);
         }