Dynamic insert into with multiple values - php

Question

This is my index.php file and it has a simple form but with jscript I'll add some more inputs dynamically, then I need to insert these inputs to my database.
<form action="insert.php" method="post">
<input type="text" name="uid" placeholder="uid">
<input type="text" name="cid_1" placeholder="cid1">
<input type="text" name="cid_2" placeholder="cid2">
<input type="submit" value="Register" name="submit" />
</form>
I've created insert.php as below. I just needed to type for each inputs but actually inputs will be added dynamically as I said, so I just need to apply while or foreach function I guess but I'm not that sure how to do, hope someone there can help me about this.
One more thing I need, In this case everything is working but it inserts everytime even if some inputs are empty. I could not found anything about this too.
Thank you for your help from now.
<?php
$link = mysqli_connect("localhost", "root", "", "test");
$uid = mysqli_real_escape_string($link, $_POST['uid']);
$cid1 = mysqli_real_escape_string($link, $_POST['cid_1']);
$cid2 = mysqli_real_escape_string($link, $_POST['cid_2']);
$sql = "INSERT INTO table (uid, cid) VALUES ('$uid', '$cid1'), ('$uid', '$cid2')";
mysqli_query($link, $sql)
?>

Answer 1

From your SQL query I understood that under uid, you are storing dynamic "cid" values from input. So you are adding dynamic input fields for "cid".
In order to capture dynamic fields on server, you have to name your input fields as given below which will be posted as an array on server.
<input type="text" name="cid[]" placeholder="cid1">
Next you will loop through that array and save each input data in your table.
Complete code:
HTML
<form action="insert.php" method="post">
<input type="text" name="uid" placeholder="uid">
<input type="text" name="cid[]" placeholder="cid1">
<input type="text" name="cid[]" placeholder="cid2">
<input type="submit" value="Register" name="submit" />
PHP
$mysqli = new mysqli('localhost','usename','password','table');
$uid = $mysqli->real_escape_string($_POST['uid']);
if($uid !== ''){
if(isset($_POST["cid"]) && is_array($_POST["cid"])){
foreach ($_POST["cid"] as $key => $value) {
$value = $mysqli->real_escape_string($value);
if($value !== ''){
// insert into table
$insert_row = $mysqli->query("INSERT INTO test ( uid, cid ) VALUES( '$uid', '$value' )");
}
else{
echo ($key+1)." no cid field is empty";
break;
}
}
}
}
else
echo "uid is empty";