Connected successfully warning: attempt to read property "num_rows" on bool in C:\xmamp\htdocs\html1\tt.php on line 19 0 results

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connected Successfully
Warning: Attempt to read property "num_rows" on bool in C:\xmamp\htdocs\html1\tt.php on line 19
0 results

this is my error and i dont know what is the wrong thing

<?php
// set connection variables
$Host_name = "localhost";
$db_user ="root";
$db_password="";
$db_name = "rmap";
// connection to server & database
$conn =new mysqli($Host_name,$db_user ,$db_password, $db_name,);
  // check connection
  if ($conn->connect_error) {
    die('Connect Error: ' . $conn->connect_error);
}
   
   echo "connected Successfully";
  
$sql = "SELECT Forward,Left,Right,Backward,Stop FROM mymap";
$result = mysqli_query($conn, $sql);

if ($result->num_rows > 0){
  // output data of each row
  while(($row = $result->fetch_assoc()) !== null) {
    echo "Forward: " . $row["Forward"]. " - Left: " . $row["Left"]. "Righ: " . $row["Right"]."Backward: " . $row["Backward"]."Stop: " . $row["Stop"]."<br>";
} }else{
  echo "0 results";
}
$conn->close();
?>

What I have tried:

i tried many thing but nothing work

Posted 30-Jun-21 7:11am

alanuod moh

Updated 9-Nov-22 4:54am

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Richard Deeming · Answer 1 · 2021-06-30T22:29:00

Read the documentation:

PHP: mysqli::query - Manual[^]:

Returns false on failure. For successful queries which produce a result set, such as SELECT, SHOW, DESCRIBE or EXPLAIN, mysqli_query() will return a mysqli_result object.

Since your query is a SELECT, and the return value is a bool, that means your query failed.

Assuming the table and column names are correct, the most likely cause is that you've used a "reserved word" as a column name:
MySQL :: MySQL 8.0 Reference Manual :: 9.3 Keywords and Reserved Words[^]

Left, Right, and Stop are all listed as reserved words. You will need to quote the names in order to select them.

SQL

SELECT Forward, `Left`, `Right`, Backward, `Stop` FROM mymap