global $wpdb displaying garbage data along with results of my select query - php

Question

I have a custom table in MySQL database, which I am trying to query using global $wpdb. I have defined my query using information available from the following two sources:
https://codex.wordpress.org/Class_Reference/wpdb
https://wordpress.stackexchange.com/questions/233021/display-data-on-word-press-site-posts-and-pages-from-mysql-table
This is how the data is in phpMyAdmin:
The query seems to be working fine as it selects data from my custom table, however the output seems to contain garbage/unnecessary information apart from the information that is available in the table.
I want it to display as a table/similar to how it is displayed in phpMyAdmin, where I am able to associate the SrNo, Compound etc with other columns in the table:
add_shortcode('wpse_233031_shortcode', function(){
global $wpdb;
$myrows = $wpdb->get_results( "SELECT `SrNo`, `Compound` FROM PNaphtha");
//$results = $wpdb->get_results( "SELECT `SrNo`, `Compound` FROM PNaphtha" );
ob_start();
echo var_dump($myrows );
//return ob_get_clean();
});
I get the following results
array(10) {
[0]=> object(stdClass)#6275 (2) {
["SrNo"]=> string(1) "2"
["Compound"]=> string(12) "abietic acid"
}
[1]=> object(stdClass)#6274 (2) {
["SrNo"]=> string(1) "3"
["Compound"]=> string(12) "acenaphthene"
}
[2]=> object(stdClass)#6273 (2) {
["SrNo"]=> string(1) "4"
["Compound"]=> string(6) "acetal"
}
[3]=> object(stdClass)#6272 (2) {
["SrNo"]=> string(1) "5"
["Compound"]=> string(12) "acetaldehyde"
}
[4]=> object(stdClass)#6271 (2) {
["SrNo"]=> string(1) "6"
["Compound"]=> string(9) "acetamide"
}
[5]=> object(stdClass)#6270 (2) {
["SrNo"]=> string(1) "7"
["Compound"]=> string(11) "acetanilide"
}
[6]=> object(stdClass)#6269 (2) {
["SrNo"]=> string(1) "8"
["Compound"]=> string(11) "acetic acid"
}
[7]=> object(stdClass)#6268 (2) {
["SrNo"]=> string(1) "9"
["Compound"]=> string(16) "acetic anhydride"
}
[8]=> object(stdClass)#6267 (2) {
["SrNo"]=> string(2) "10"
["Compound"]=> string(7) "acetone"
}
[9]=> object(stdClass)#6266 (2) {
["SrNo"]=> string(2) "11"
["Compound"]=> string(19) "acetone cyanohydrin"
}
}
Although, all of the information I queried is available here, there is also a lot of unnecessary information.
I tried the following changes, however none of them seems to be working
$myrows = $wpdb->get_row( "SELECT `SrNo`, `Compound` FROM PNaphtha"); // get_row
output_type changed to ARRAY_A, ARRAY_N, OBJECT_K
echo var_dump changed to echo array
I will appreciate if you could please advise on how to get the results to format as a table or array. Also, I have placed the above code in the functions.php file of my theme. Is there a better way to do this?

Answer 1

So, you're getting object as output, that's why you're seeing that information in there. Make the following change. Add 'ARRAY_A' (associative array) to the end of your function call.
$wpdb->get_results( "SELECT `SrNo`, `Compound` FROM PNaphtha", ARRAY_A);
That will keep your query from being returned as an object and your var_dump will look the way you expect.

Answer 2

It may be because you are using var_dump
The var_dump function displays structured information about variables/expressions including its type and value.
I would recommend using print_r
The print_r() displays information about a variable in a way that's readable by humans. array values will be presented in a format that shows keys and elements.
You should be able to see a change if you change
var_dump($myrows )
to
print_r($myrows)
Here's how I did what you are wanting (Without echoing the result):
$sql = "SELECT `Srno`,`compound` FROM `pnaphtha`";
$result = $conn->query($sql);
echo "<table>";
while($row = $result->fetch_assoc()) {
echo "<tr><td>".$row['Srno']."</td><td>".$row['compound']."</td></tr>";
}
echo "</table>";
However since you are using WordPress I would suspect it would be something along the lines of
global $wpdb;
$sql = "SELECT `SrNo`, `Compound` FROM PNaphtha";
//you may need to add ARRAY_A
$myrows = $wpdb->get_results($sql);
echo "<table>";
while($myrows = $result->fetch_assoc()) {
echo "<tr><td>".$myrows['SrNo']."</td><td>".$myrows['Compound']."</td></tr>";
}
echo "</table>";
I can't actually test the wordpress version as I can't be bothered to set up a wordpress install haha