如何调试不再起作用的PHP / SQL代码？

Question

I'm new to PHP but have the code below. It essentially should load some values into an array from an SQL query then use the values in the array to output from another query. Loop within a loop.

Oddly it did work at first but now doesn't. If I separate the two queries they still work fine. So no database issues, and no error messages given. I just want to know if it's OK to use this method as it seems the easiest. Or do I have to separate the loops out?

$sql = 'SELECT menuID FROM explore_section1 WHERE menukey="sea-ovr"';
$place = $conn->query($sql);
while($row = $place->fetch_assoc()) {
  $sql2 = 'SELECT url, name FROM explore_items WHERE menuID="'.$row["menuID"].'"';
  $result = $conn->query($sql2);
  while($row2 = $result->fetch_assoc()) {
    echo '<li><a href="'.$row2["url"].'">'.$row2["name"].'</a></li>';
  }     
}   

Thanks!

Answer 1

I don't see any reason for 2 queries, just that simple:

$sql = 'SELECT s.menuID, i.url, i.name 
        FROM explore_section1 s
        LEFT JOIN explore_items i
        ON s.menuID = i.menuID
        WHERE s.menukey="sea-ovr"';
if($result = $conn->query($sql)) {
    while($row = $result->fetch_assoc()) {
        echo '<li><a href="'.$row["url"].'">'.$row["name"].'</a></li>';
    }
} else { 
    echo "Error:". $conn->error);
}

UPDATE Query should work: http://sqlfiddle.com/#!9/76f2f/1

Answer 2

OK, after hours of playing. MySQL has a weird thing. I was importing the data as nearly everywhere advises using the following structure queries:

LOAD DATA LOCAL INFILE 'C:/data.csv' INTO TABLE explore_items
FIELDS TERMINATED BY ','
ENCLOSED BY ';'
LINES TERMINATED BY '\n'
(field1, field2);

This looked to work fine and queries work if using just one table but soon as you join them they don't work. ODD!! The way I have to import the data is as per the import instructions below (found in another thread):

phpMyAdmin has the necessary tool to handle CSV import. Here are the steps to follow:

• prepare the CSV file to have the fields in the same order as the MySQL table fields

• remove the header row from CSV (if any), so only data is there in file go to phpMyAdmin interface select the table in left menu

• click the import button at top

• browser the CSV file

• select the option "CSV using LOAD DATA"

• enter "," in the "fields terminated by"

• enter the column names in the same order as they are in db table

• click go button and you are done.

Thanks @Alex for all your time on that one!!