diff --git a/Script.php b/Script.php
index f664eee..9fdb69b 100644
--- a/Script.php
+++ b/Script.php
@@ -913,18 +913,32 @@ if (!empty($_GET["ignoreremarking"])) {
 #Assign TA
 
 if (!empty($_GET["assignTA"])) {
-
     $id = mysqli_real_escape_string($con, $_GET["id"]);
     $ta = mysqli_real_escape_string($con, $_GET["ta"]);
 
-    $sql = "INSERT INTO `course_ta`(`Course_ID`, `TA`) VALUES ('$id','$ta')";
+    // Check if the TA is already assigned to the course
+    $check_sql = "SELECT * FROM course_ta WHERE Course_ID='$id' AND TA='$ta'";
+    $check_result = $con->query($check_sql);
 
-    if ($con->query($sql) === TRUE) {
-
-        $_SESSION["info_Admin_Courses"] = $type . " Course TA Assigned ";
-        header("Location: Admin.php");
+    if ($check_result->num_rows > 0) {
+        // Alert user about the duplicate assignment
+        echo "<script>
+            alert('The selected TA is already assigned to this course.');
+            window.location.href='Admin.php';
+        </script>";
     } else {
-        echo "Error: " . $sql . "<br>" . $con->error;
+        // Proceed with the TA assignment
+        $sql = "INSERT INTO course_ta(Course_ID, TA) VALUES ('$id','$ta')";
+
+        if ($con->query($sql) === TRUE) {
+            $_SESSION["info_Admin_Courses"] = $type . " Course TA Assigned ";
+            header("Location: Admin.php");
+        } else {
+            echo "<script>
+                alert('You must select a TA first!.');
+                window.location.href='Admin.php';
+            </script>";
+        }
     }
 }
 
diff --git a/test/SeleniumMpiana/test_assign_ta.py b/test/SeleniumMpiana/test_assign_ta.py
new file mode 100644
index 0000000..50d9e49
--- /dev/null
+++ b/test/SeleniumMpiana/test_assign_ta.py
@@ -0,0 +1,125 @@
+import pytest
+from selenium import webdriver
+from selenium.webdriver.common.by import By
+from selenium.webdriver.support.ui import Select
+from selenium.webdriver.support.ui import WebDriverWait
+from selenium.webdriver.support import expected_conditions as EC
+from selenium.common.exceptions import NoSuchElementException, UnexpectedAlertPresentException
+from selenium.webdriver.common.keys import Keys
+
+# New instance of the Chrome driver
+driver = webdriver.Chrome()
+
+# Open the login page
+driver.get("http://localhost/lrr/admin.php")
+
+# Credentials for login
+username = "lanhui@qq.com"
+password = "admin123"
+
+def login(driver, username, password):
+    try:
+        # Fill in the login form
+        user_input = WebDriverWait(driver, 10).until(
+            EC.element_to_be_clickable((By.ID, "user_name"))
+        )
+        user_input.send_keys(username)
+
+        password_input = WebDriverWait(driver, 10).until(
+            EC.element_to_be_clickable((By.ID, "user_password"))
+        )
+        password_input.send_keys(password)
+
+        # Click the login button
+        login_button = WebDriverWait(driver, 10).until(
+            EC.element_to_be_clickable((By.ID, "login_btn"))
+        )
+        login_button.click()
+
+        # Wait for the admin_tab to become clickable
+        admin_tab = WebDriverWait(driver, 10).until(
+            EC.element_to_be_clickable((By.ID, "admin_tab"))
+        )
+
+        return True
+
+    except (NoSuchElementException, UnexpectedAlertPresentException) as e:
+        return f"Error: {str(e)}"
+
+# Call the login function
+login_result = login(driver, username, password)
+
+# Click on admin_tab after successful login
+if login_result:
+    admin_tab = WebDriverWait(driver, 10).until(
+        EC.element_to_be_clickable((By.ID, "admin_tab"))
+    )
+    admin_tab.click()
+
+    # Optionally, wait for the Admin.php page to load
+    admin_url = "http://localhost/lrr/Admin.php"
+    WebDriverWait(driver, 15).until(
+        EC.url_to_be(admin_url)
+    )
+
+print(login_result)
+
+def assign_ta(driver, course_id, ta_name):
+    try:
+        # Locate the form and select the TA
+        ta_form = WebDriverWait(driver, 15).until(
+            EC.presence_of_element_located((By.XPATH, f"//form[@id='drop_menu_form_{course_id}']"))
+        )
+
+        ta_dropdown = Select(ta_form.find_element(By.XPATH, ".//select[@name='ta']"))
+        ta_dropdown.select_by_visible_text(ta_name)
+
+        # Submit the form using JavaScript
+        driver.execute_script("arguments[0].submit();", ta_form)
+
+        # Wait for an expected alert and accept it
+        WebDriverWait(driver, 10).until(EC.alert_is_present())
+        alert = driver.switch_to.alert
+        alert_text = alert.text
+        alert.accept()
+
+        return alert_text
+
+    except UnexpectedAlertPresentException as e:
+        # Unexpected alert, handle it as an error
+        return f"Error: Unexpected alert - {str(e)}"
+
+    except (NoSuchElementException, Exception) as e:
+        return f"Error: {str(e)}"
+
+
+
+# The courses and test cases to test
+courses_to_test = [
+    {"id": 1, "name": "Teecloudy - Ashly Course Testing", "ta_assignments": {"JAMES": "Ta assigned successfully."}},
+    {"id": 2, "name": "P.M2019 - Project Management", "ta_assignments": {"JAMES": "The selected TA is already assigned to this course."}},
+]
+
+# Execute the tests
+@pytest.mark.parametrize("course", courses_to_test)
+def test_assign_ta(course):
+    for ta_name, expected_result in course["ta_assignments"].items():
+        alert_text = assign_ta(driver, course["id"], ta_name) 
+        # ----- ---- Print the raw strings for debugging ----- ---- --- 
+        test_case_number = courses_to_test.index(course) + 1
+        print(f"Test Case {test_case_number} - {course['name']} -- {ta_name}: Expected Result={expected_result}, Actual Alert Text={alert_text}")
+
+        # Determine the result based on the comparison
+        if expected_result.lower() in alert_text.lower():
+            result = "Passed"
+        else:
+            result = "Failed"
+
+        # Write the result to a test file with test case number ---
+        with open("test_results.txt", "a") as file:
+            file.write(f"Test Case {test_case_number} - {course['name']} -- {ta_name}: Result={result}, Expected Result={expected_result}, Actual Alert Text={alert_text}\n")
+
+        # Print the result to the console --- 
+        print(f"Test Case {test_case_number} - {course['name']} -- {ta_name}: Result={result}, Expected Result={expected_result}, Actual Alert Text={alert_text}")
+
+        assert result == "Passed", f"Test Case {test_case_number} failed: Result={result}, Expected Result={expected_result}, Actual Alert Text={alert_text}"
diff --git a/test/SeleniumMpiana/test_results.txt b/test/SeleniumMpiana/test_results.txt
new file mode 100644
index 0000000..4f55332
--- /dev/null
+++ b/test/SeleniumMpiana/test_results.txt
@@ -0,0 +1,2 @@
+Test Case 1 - Teecloudy - Ashly Course Testing -- JAMES: Result=Passed, Expected Result=Ta assigned successfully., Actual Alert Text=TA assigned successfully.
+Test Case 2 - P.M2019 - Project Management -- DIEGO: Result=Passed, Expected Result=The selected TA is already assigned to this course., Actual Alert Text=The selected TA is already assigned to this course.