这个MySQL查询和PHP foreach有什么问题

Question

Please help me learn what is wrong with this PHP / MySQL query.

This is my channels table:

name    url              id      key
BBC2    http://url.com/2 BBC2   2
BBC1    http://url.com/1 BBC1   1

This works:

$getchans = "SELECT * FROM channels";  
$channels = mysqli_query($db,$getchans);    
foreach ($channels as $channel)
{
    // do stuff 
}

This does not work:

$getchans = "SELECT * FROM channels ORDER BY key ASC";  
$channels = mysqli_query($db,$getchans);    
foreach ($channels as $channel)
{
    // do stuff 
}

and gives error Warning: Invalid argument supplied for foreach()

Can anyone please tell me why it doesn't work when MySQL query/result is ordered?

Thank you.

Answer 1

esacepe关键字关键字， 请参阅

$getchans="SELECT * FROM channels ORDER BY `key` ASC";  

Answer 2

key is a keyword in mysql so you need to use `` quotes in your query.

$getchans="SELECT * FROM channels ORDER BY key ASC";

Answer 3

Your query failed because key is a reserved keyword in SQL. Try to change the name of the column key to something else. There is also a very usefull list with all the reseverd keywords.

If you don't prefer an other name for this column, you can try to escape it by using the following query:

SELECT * FROM channels ORDER BY `key` ASC

List with reserved keywords can be found on https://dev.mysql.com/doc/refman/5.7/en/keywords.html

Goodluck!