How to display echo if user has not selected from a drop down menu <p>In my code below I have 2 drop down menus. One is a "Course" drop down menu and the other is a "Modules" drop down menu:</p> <p>Below is the code:</p> <pre><code> &lt;?php // connect to the database include('connect.php'); /* check connection */ if (mysqli_connect_errno()) { printf("Connect failed: %s\n", mysqli_connect_error()); die(); } $sql = "SELECT CourseId, CourseName FROM Course ORDER BY CourseId"; $sqlstmt=$mysqli-&gt;prepare($sql); $sqlstmt-&gt;execute(); $sqlstmt-&gt;bind_result($dbCourseId, $dbCourseName); $courses = array(); // easier if you don't use generic names for data $courseHTML = ""; $courseHTML .= '&lt;select name="courses" id="coursesDrop" onchange="getModules();"&gt;'.PHP_EOL; $courseHTML .= '&lt;option value=""&gt;Please Select&lt;/option&gt;'.PHP_EOL; while($sqlstmt-&gt;fetch()) { $course = $dbCourseId; $coursename = $dbCourseName; $courseHTML .= "&lt;option value='".$course."'&gt;" . $course . " - " . $coursename . "&lt;/option&gt;".PHP_EOL; } $courseHTML .= '&lt;/select&gt;'; $moduleHTML = ""; $moduleHTML .= '&lt;select name="modules" id="modulesDrop"&gt;'.PHP_EOL; $moduleHTML .= '&lt;option value=""&gt;Please Select&lt;/option&gt;'.PHP_EOL; $moduleHTML .= '&lt;/select&gt;'; include('noscript.php'); ?&gt; &lt;script type="text/javascript"&gt; function getModules() { var course = jQuery("#coursesDrop").val(); jQuery('#modulesDrop').empty(); jQuery('#modulesDrop').html('&lt;option value=""&gt;Please Select&lt;/option&gt;'); jQuery.ajax({ type: "post", url: "module.php", data: { course:course }, success: function(response){ jQuery('#modulesDrop').append(response); } }); } &lt;/script&gt; &lt;h1&gt;EDIT AN ASSESSMENT'S DATE/START TIME&lt;/h1&gt; &lt;form action="&lt;?php echo htmlentities($_SERVER['PHP_SELF']); ?&gt;" method="post"&gt; &lt;table&gt; &lt;tr&gt; &lt;th&gt;Course: &lt;?php echo $courseHTML; ?&gt;&lt;/th&gt; &lt;th&gt;Module: &lt;?php echo $moduleHTML; ?&gt;&lt;/th&gt; &lt;/tr&gt; &lt;/table&gt; &lt;p&gt;&lt;input id="moduleSubmit" type="submit" value="Submit" name="moduleSubmit" /&gt;&lt;/p&gt; &lt;/form&gt; &lt;?php if (isset($_POST['moduleSubmit'])) { $sessionquery = " SELECT SessionId, SessionDate, SessionTime, ModuleId, TeacherId FROM Session WHERE (ModuleId = ? AND TeacherId = ?) ORDER BY SessionDate, SessionTime "; $sessionqrystmt=$mysqli-&gt;prepare($sessionquery); // You only need to call bind_param once $sessionqrystmt-&gt;bind_param("si",$moduleId,$userid); // get result and assign variables (prefix with db) $sessionqrystmt-&gt;execute(); $sessionqrystmt-&gt;bind_result($dbSessionId,$dbSessionDate,$dbSessionTime, $dbModuleId, $dbTeacherId); $sessionqrystmt-&gt;store_result(); $sessionnum = $sessionqrystmt-&gt;num_rows(); if($sessionnum ==0){ echo "&lt;p&gt;Sorry, You have No Sessions under this Module&lt;/p&gt;"; </code></pre> <p>module.php where it displays "Module" drop down menu:</p> <pre><code> &lt;?php // connect to the database include('connect.php'); /* check connection */ if (mysqli_connect_errno()) { printf("Connect failed: %s\n", mysqli_connect_error()); die(); } $course = isset($_POST['course']) ? $_POST['course'] : ''; $sql = " SELECT cm.CourseId, cm.ModuleId, c.CourseName, m.ModuleName FROM Course c INNER JOIN Course_Module cm ON c.CourseId = cm.CourseId JOIN Module m ON cm.ModuleId = m.ModuleId WHERE (c.CourseId = ?) ORDER BY c.CourseId, m.ModuleId "; $sqlstmt=$mysqli-&gt;prepare($sql); $sqlstmt-&gt;bind_param("s",$course); $sqlstmt-&gt;execute(); $sqlstmt-&gt;bind_result($dbCourseId,$dbModuleId,$dbCourseName,$dbModuleName); $moduleHTML = ""; while($sqlstmt-&gt;fetch()) { $moduleHTML .= "&lt;option value='$dbModuleId'&gt;" . $dbModuleId . " - " . $dbModuleName . "&lt;/option&gt;".PHP_EOL; } echo $moduleHTML; $sqlstmt-&gt;execute(); ?&gt; </code></pre> <p>Now if you look at the bottom of the code, what happens is that it performs a query after the user has submitted the "Course" and "Module" drop down menus. if it doesn't find a session related with that module then it echos <code>"Sorry, You have No Sessions under this Module"</code>. </p> <p>But what my question is that I do not want this echo to be displayed if the user has not selected a "Course" and "Module" from their drop down menus or if the user has selected a course from the "Course" drop down menu but has not selected a module from the "Module" drop down menu.</p> <p>Below is the echo's I wanted for each situation:</p> <ol> <li>If user has not selected a course and a module: <code>echo "Please Select a Course and Module";</code></li> <li>If user has selected a course but not a module: <code>echo "Please Select a Module";</code></li> <li>If user has selected a course and module but no sessions appear: <code>echo "Sorry, You have No Sessions under this Module";</code></li> </ol> <p>List 3 from above at the moment works but how can I get list 1 and 2 to work by only displaying their echo's and no other echo?</p> <p><strong>UPDATE:</strong></p> <p>Javascript code where it validates drop down menus:</p> <pre><code> function validation() { var isDataValid = true; var moduleTextO = document.getElementById("coursesDrop"); var courseTextO = document.getElementById("modulesDrop"); var errModuleMsgO = document.getElementById("moduleAlert"); if (courseTextO.value == "" &amp;&amp; moduleTextO.value == ""){ errModuleMsgO.innerHTML = "Please Select a Course and Module"; isDataValid = false; } else if (courseTextO.value == ""){ errModuleMsgO.innerHTML = "Please Select a Course"; isDataValid = false; }else if (moduleTextO.value == ""){ errModuleMsgO.innerHTML = "Please Select a Module"; isDataValid = false; }else{ errModuleMsgO.innerHTML = ""; } return isDataValid; } </code></pre> <p>Below is HTML code:</p> <pre><code>&lt;form action="&lt;?php echo htmlentities($_SERVER['PHP_SELF']); ?&gt;" method="post"&gt; &lt;table&gt; &lt;tr&gt; &lt;th&gt;Course: &lt;?php echo $courseHTML; ?&gt;&lt;/th&gt; &lt;th&gt;Module: &lt;?php echo $moduleHTML; ?&gt;&lt;/th&gt; &lt;/tr&gt; &lt;/table&gt; &lt;p&gt;&lt;input id="moduleSubmit" type="submit" value="Submit" name="moduleSubmit" /&gt;&lt;/p&gt; &lt;div id="moduleAlert"&gt;&lt;/div&gt; &lt;/form&gt; </code></pre>