新增错误提示

src/main/java/com/web/web_assignment/DatabaseService.java

@@ -215,6 +215,9 @@ public class DatabaseService {
                     int count = rs.getInt(1);
 
                     if (count > 0) {
+                        if (count>1){
+                            throw new SQLException("Duplicate project found");
+                        }
                         String updateSql = "UPDATE projects SET summary = ?, description = ?, keywords = ?, type = ?, collaborators = ?, link = ?, time = ? WHERE title = ? AND user_id = (SELECT id FROM users WHERE username = ?)";
                         try (PreparedStatement updateStmt = conn.prepareStatement(updateSql)) {
                             updateStmt.setString(1, project.getSummary());

src/main/java/com/web/web_assignment/ProjectBean.java

@@ -151,6 +151,7 @@ public class ProjectBean implements Serializable {
             context.addMessage("saveButton", new FacesMessage(FacesMessage.SEVERITY_INFO, "Submission Succeeded", null));
             loadAllKeywords();
         } catch (SQLException e) {
+            context.addMessage("saveButton", new FacesMessage(FacesMessage.SEVERITY_ERROR, "Submission Failed", null));
             e.printStackTrace();
         }
         return "project";