Use PHP to get values in option value - php

Question

I want to get the value of the option using PHP, and depending on the chosen option i want the page to display different results depending on what they choose.
I do not have a submit button as i want the data to change when the user clicks on an option from the drop down list.
Here is my form:
<form action="#" name="viewall" id="viewall" method="post">
<label for="date" id="date">Select a decade:</label>
<select name="date">
<option value="all" id="all">View All</option>
<option value="1920" id="1920">1920's</option>
<option value="1930" id="1930">1930's</option>
<option value="1940" id="1940">1940's</option>
<option value="1950" id="1950">1950's</option>
<option value="1960" id="1960">1960's</option>
<option value="1970" id="1970">1970's</option>
<option value="1980" id="1980">1980's</option>
<option value="1990" id="1990">1990's</option>
</select>
And i would like if the user picks 1920's that it only shows records in that decade, if the user doesn't pick anything it will automatically show all records.
I have been trying to use the following code and kind of got it working using submit button, but it would only show either 1920's or 1970's and wouldn't change.
if(isset($_POST['submit'])){
//sel_val stores selected value in a variable
//mysqli_real_escape_string() function escapes special characters in a string for use in an SQL statement.
$sel_val = mysqli_real_escape_string($con, $_POST['1920']);
$sql = mysqli_query($con, "SELECT * FROM details
WHERE year < '1930' AND year > '1919' ORDER BY year ASC;");
}
elseif(isset($_POST['submit'])){
//sel_val stores selected value in a variable
//mysqli_real_escape_string() function escapes special characters in a string for use in an SQL statement.
$sel_val = mysqli_real_escape_string($con, $_POST['1970']);
$sql = mysqli_query($con, "SELECT * FROM details
WHERE year < '1980' AND year > '1969' ORDER BY year ASC;");
}
else
{
$sel_val = mysqli_real_escape_string($con, $_POST['all']);
$sql = mysqli_query($con, "SELECT * FROM details ORDER BY year ASC;") or die(mysqli_error($con));
}
Any suggestions with or without a submit button would help.

Answer 1

if (isset($_POST['submit'])) {
if (is_numeric($_POST['date']) {
$sel_val = mysqli_real_escape_string($con, $_POST['date']);
$sql = mysqli_query($con, "SELECT * FROM details WHERE year = " . $sel_val);
} elseif ($_POST['date'] === 'all') {
$sql = mysqli_query($con, "SELECT * FROM details ORDER BY year ASC");
}
} else {
$sql = mysqli_query($con, "SELECT * FROM details ORDER BY year ASC;") or die(mysqli_error($con));
}

Answer 2

The reason you only get 20's or 70's is because that is all that is coded in the case statement. If those actually worked, you just need to code a few more conditions. Change the date values by 10 years for each until you get all the decades.
You will need AJAX to do this without a submit. To learn more about AJAX please see jQuery's AJAX or if you prefer Javascript and Mozilla Documentation You can also search on the numerous posts on StackOverflow to learn what other users have gone through!