将PHP数组中的值插入到mySQL行中

I'm exploding a comma separated list into a variable named $tagArray and trying to write those values into incrementing rows of a table.

The code below works in so much as it creates the appropriate number of rows in my table but it only writes the first letter of the comma separating string (ie. if the string reads as "one, two, three", "o" is written in the first row and the remaining two rows have a blank value for column "blog_tag":

$tagInput = $_POST["blog_tags"];
$tagArray = explode(",",$tagInput);

$sql_2 = "INSERT INTO blog_tags (blog_tag, blog_id)
VALUES ";

$valuesArray = array();
foreach($tagArray as $row){
$tag = mysqli_real_escape_string($conxn, $row['blog_tag']);
$valuesArray[] = "('$tag','$lastID')";
}

$sql_2 .= implode(',', $valuesArray);

if (!mysqli_query($conxn,$sql_2)) {
die('Error: ' . mysqli_error($conxn));
}

This is spaghetti pieced together from various searches here and it's getting close but I can't figure out where it's grabbing just that first letter of the string.

Explode doesn't create associative arrays

$tag = mysqli_real_escape_string($conxn, $row); //instead of $row['blog_tag']

just replace your foreach with this for inserting values of array

foreach($tagArray as $row){
  $a=mysqli_real_escape_string($row)
$sql_2 = "INSERT INTO blog_tags (blog_tag, blog_id) VALUES 
  ('$a','$lastID') ";
}