How to insert an array into a single MySQL Prepared statement w/ PHP and PDO

Question

During an online enrollment, a customer may select a number of programs which they choose to enroll for. These programs are three digit integers and are stored in an array.

For example:

I want to enroll in programid 155, 165, 175, and 185.

My array is set up as simple as:

$data = array();

$data[] = 155;

$data[] = 165;

$data[] = 175;

$data[] = 185;

When it comes time to insert this information into the associated table, I also include additional elements from the other part of the enrollment:

For example, if I were doing a SINGLE program insert statement, it would look as follows:

$stmt = $db->prepare("INSERT INTO table SET memberID=?, programID=?, date_added=NOW()");
$stmt->execute(array($memberid, 155));

I would normally create a simple loop for the array above which would call multiple instances of the sql statement and execute such as:

for($j = 0; $j < (count($data)-1); $j++) {
   $stmt = $db->prepare("INSERT INTO table SET memberID=?, programID=?, date_added=NOW()");
   $stmt->execute(array($memberid, $data[$j]));
}

I do realize the code above is invalid ( $data[$j] ) but looking for the right way to do the call.

I have also been told before that building a single dynamic sql statement is overall better than multiple calls like above. My first pass would be something like:

$sql = array(); 
foreach( $data as $row ) {
    $sql[] = '("'.$memberid.'", "'.$row[$j].'", NOW()")';
}
mysql_real_query('INSERT INTO table (memberid, programid) VALUES '.implode(',', $sql));

but with PDO I am not quite sure how this works, especially with placeholders (?).

Any suggestions?

Solution 1

You could build the query programatically...:

$sql = 'INSERT INTO table (memberID, programID) VALUES ';
$insertQuery = array();
$insertData = array();
foreach ($data as $row) {
    $insertQuery[] = '(?, ?)';
    $insertData[] = $memberid;
    $insertData[] = $row;
}

if (!empty($insertQuery)) {
    $sql .= implode(', ', $insertQuery);
    $stmt = $db->prepare($sql);
    $stmt->execute($insertData);
}

Solution 2

2 solutions

// multiple queries
$stmt = $pdo->prepare('INSERT INTO table SET memberID=:memberID, programID=:programID, date_added=NOW()');
$data = array(155, 165, 175, 185);
foreach($data as $d) {
    $stmt->execute(array(':memberID' => $memberid, ':programID' => $d));
}

And

// one query
$data = array(155, 165, 175, 185);
$values = array();
foreach($data as $d) {
    $values[] = sprintf('(%d, %d, NOW())', $d, $memberid);
}
$sql = sprintf('INSERT INTO table (memberID, programID, date_added) VALUES %s', implode (', ', $values));
$pdo->exec($sql);

Comments

[JM4]

thanks for your post, although, isnt the first answer above making multiple queries and taxing the database more than the latter? (most have told me not to use as such). I will test the latter as it seems to probably fit my needs better. Of note: i have zero problem doing multiple queries, only have been told it is 'slower' (with a max of 8 records, one second means nothing to me).

[JM4]

thanks for the suggestion. I am toying with it right now. The implode is throwing an error but I'll let you know what comes up.

[JM4]

great. thanks for the help! Thinking through the date_added in the example above, creating a new $insertdata[] = NOW() element would not insert properly (as PDO would treat that as a varchar input and treat it literally instead of mysql date format. Normally I would simply generate the query: date_added = NOW() but with the values as above, can this be done? I do realize I could simply run php date(Y-m-d H:i:s) but wanted to see if NOW() were possible.

[Xavier Barbosa]

The multiple queries are slower about ten milliseconds, but they are more readable and easier to debug.

[Admin]

You make it so simple +1. Respect