PHP - for statement in a string - php

Question

I have a MySQL statement that I want to execute and inside this statement I would like to include a for loop to define the columns that data will be entered into etc.
The code I currently have is
$stmt = $conn->prepare('INSERT into DATA ('.
for($i = 0; $i < count($columns); $i++) {
echo $columns[$i];
}
.') VALUES ('.
for($i = 0; $i < count($columns); $i++) {
echo ':'.$columns[$i].' , ';
}
.')');
Obviously this doesn't work but if it was to work also in the second for statement it echos a comma at the end of each loop, which will cause an error for the last loop so also is there a way to fix this to?
Thanks in advance!

Answer 1

Use the join/implode function:
$params = array_map(function($var){return ':'.$var;}, $columns);
$sql = 'INSERT into DATA ('.join(',', $columns).') VALUES ('.join(',', $params).')';
$stmt = $conn->prepare($sql);

Answer 2

Another approach using implode:
$sql = "INSERT into DATA (`" . implode('`,`', $columns) . "`) values (:" . implode(',:', $columns) . ")"
$stmt = $conn->prepare($sql);
Example result:
// Input array
$columns = array('A', 'B', 'C');
// Output
INSERT into DATA(`A`,`B`,`C`) values (:A,:B,:C)

Answer 3

You should create the query outside of the prepare() function to make it easier.
Something like that would be better/clearer :
$count = count ($columns); // Avoid using count in your loop init (Performances)
$query = 'INSERT INTO DATA (' .
for($i = 0; $i < $count; $i++) {
$query .= $columns[$i];
}
$query .= ') VALUES (';
for($i = 0; $i < $count; $i++) {
if ($i != $count - 1) $query.= ':'.$columns[$i].' , ';
else $query .= ':'.$columns[$i]; // No coma for the last value
}
$query .= ')';
$stmt = $conn->prepare($query);