INNER JOIN and foreach loop on php and mysql

Question

I have problem with foreach loop and inner join on php. I have two tables: toners and printers. And code:

$toner = $this->_db->execute('SELECT TONERS.NAME, PRINTERS.NAME, TONERS.CONTRACTORS FROM TONERS INNER JOIN PRINTERS ON TONERS.ID_PRINTERS=PRINTERS.ID;')
foreach ($toner as $toners) {
            //here is the html table with results
}

receives an error: Warning: Invalid argument supplied for foreach(). I'll add that on the query without 'Inner join' everything works fine ...

Anyone have an idea? Please...

Apparently, query return less than or equal to one row – Sakezzz Jul 12 '18 at 05:00 — Sakezzz, Jul 12 '18 at 05:00

score 3 · Accepted Answer · answered Jul 12 '18 at 05:07

3

foreach fails like this if $toner is null. The inner join is returning no rows. You need logic to handle this case. See this question for more info about this error.

answered Jul 12 '18 at 05:07

Eric M. Johnson

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score 0 · Answer 2 · answered Jul 12 '18 at 07:19

At first, try to run this query on a server (like in PHPMyAdmin) and check that there are some records to fill your variable, which is used in foreach loop. This error shows you that your $toner var is empty.

Then try to fetch data from your query

$sql = "SELECT TONERS.NAME, PRINTERS.NAME, TONERS.CONTRACTORS FROM TONERS INNER JOIN PRINTERS ON TONERS.ID_PRINTERS=PRINTERS.ID;";
$result = $conn->query($sql);
while($row = $result->fetch_assoc()) {
     //do your magic
}

INNER JOIN and foreach loop on php and mysql

2 Answers2