diff --git a/src/core/marketplace.cpp b/src/core/marketplace.cpp
index 5e46bf3..ded680f 100644
--- a/src/core/marketplace.cpp
+++ b/src/core/marketplace.cpp
@@ -41,4 +41,15 @@ int Marketplace::getNumSellersDelete()
     return count;
 }
 
-void Marketplace::sortSellers() { std::sort(sellers_.begin(), sellers_.end()); }
\ No newline at end of file
+void Marketplace::sortSellers() { std::sort(sellers_.begin(), sellers_.end()); }
+
+Seller* Marketplace::findSellerWithSellerNo(int sellerNo)
+{
+    auto iter =
+        std::find_if(sellers_.begin(), sellers_.end(), [sellerNo](const auto& a) {
+            return a->getSellerNo() == sellerNo;
+        });
+    if (iter == sellers_.end())
+        return nullptr;
+    return (*iter).get();
+}
\ No newline at end of file
diff --git a/src/core/marketplace.h b/src/core/marketplace.h
index 9d76168..139579f 100644
--- a/src/core/marketplace.h
+++ b/src/core/marketplace.h
@@ -26,6 +26,7 @@ class Marketplace
     int getNextSellerNo();
     int getNumSellersDelete();
     void sortSellers();
+    Seller* findSellerWithSellerNo(int sellerNo);
 
   private:
     SellersVec sellers_;
diff --git a/src/gui/mainwindow.cpp b/src/gui/mainwindow.cpp
index a0ad153..4146441 100644
--- a/src/gui/mainwindow.cpp
+++ b/src/gui/mainwindow.cpp
@@ -2,6 +2,8 @@
 
 #include "sellerdialog.h"
 
+#include <regex>
+
 constexpr int STATUSBAR_TIMEOUT = 5000;
 
 MainWindow::MainWindow()
@@ -11,6 +13,8 @@ MainWindow::MainWindow()
     connect(ui_.actionQuit, &QAction::triggered, qApp, QApplication::quit);
     connect(ui_.actionEditSeller, &QAction::triggered, this,
             &MainWindow::on_actionEditSeller_triggered);
+    connect(ui_.sellerNoEdit, &QLineEdit::returnPressed, this,
+            &MainWindow::on_sellerNoEdit_checkSellerNo);
 
     marketplace_ = std::make_unique<Marketplace>();
     marketplace_->loadFromDb();
@@ -31,4 +35,31 @@ void MainWindow::on_actionEditSeller_triggered()
         statusBar()->showMessage("Änderungen an den Verkäufer-Stammdaten verworfen!",
                                  STATUSBAR_TIMEOUT);
     }
+}
+
+void MainWindow::on_sellerNoEdit_checkSellerNo()
+{
+    using std::regex, std::regex_match, std::smatch;
+
+    auto inputText = ui_.sellerNoEdit->text().toStdString();
+
+    if (inputText.empty()) {
+
+        return;
+    }
+
+    regex pattern{R"(\d{1,5})"};
+    smatch result;
+    if (!regex_match(inputText, result, pattern)) {
+        return;
+    }
+    int sellerNo = std::stoi(result[0]);
+
+    auto seller = marketplace_->findSellerWithSellerNo(sellerNo);
+    if (seller) {
+        std::cout << "!!! Seller gefunden: " << seller->getFirstName() << "\n";
+        // TODO: Warenkorb füllen
+    }
+    
+    ui_.sellerNoEdit->clear();
 }
\ No newline at end of file
diff --git a/src/gui/mainwindow.h b/src/gui/mainwindow.h
index e9826b4..d6f5160 100644
--- a/src/gui/mainwindow.h
+++ b/src/gui/mainwindow.h
@@ -13,15 +13,16 @@ class MainWindow : public QMainWindow
 {
     Q_OBJECT
 
-    public:
+  public:
     MainWindow();
-    Marketplace* getMarketplace() {return marketplace_.get();}
+    Marketplace* getMarketplace() { return marketplace_.get(); }
 
-    private:
-        void on_actionEditSeller_triggered();
+  private:
+    void on_actionEditSeller_triggered();
+    void on_sellerNoEdit_checkSellerNo();
 
-        Ui::MainWindow ui_;
-        std::unique_ptr<Marketplace> marketplace_;
+    Ui::MainWindow ui_;
+    std::unique_ptr<Marketplace> marketplace_;
 };
 
 #endif
\ No newline at end of file
diff --git a/src/gui/mainwindow.ui b/src/gui/mainwindow.ui
index 1d09eae..44fe7db 100644
--- a/src/gui/mainwindow.ui
+++ b/src/gui/mainwindow.ui
@@ -52,10 +52,10 @@
         <item>
          <layout class="QHBoxLayout" name="horizontalLayout_4">
           <item>
-           <widget class="QLineEdit" name="lineEdit"/>
+           <widget class="QLineEdit" name="sellerNoEdit"/>
           </item>
           <item>
-           <widget class="QPushButton" name="pushButton_3">
+           <widget class="QPushButton" name="paidButton">
             <property name="text">
              <string>Bezahlt!</string>
             </property>