如果不存在则插入并在PHP＆MySql中获取插入ID

Question

I'm developing a PHP script and I just want to know if I can make this code piece with better performance.

I have to make 2 mysql queries to complete my task. Is there any other way to complete this with better performance?

$language = "en";
$checkLanguage      =   $db->query("select id from language where shortName='$language'")->num_rows;
if($checkLanguage>0){
    $languageSql    =   $db->query("select id from language where shortName='$language'")->fetch_assoc();
    $languageId     =   $languageSql['id'];
}else{
    $languageSql    =   $db->query("insert into language(shortName) values('$language')");
    $languageId     =   $db->insert_id;
}
echo $languageId

Answer 1

You can improve your performance, by storing the stamtement object to a variable, this way it will be one less query:

$checkLanguage      =   $db->query("select id from language where shortName='$language'");
if($checkLanguage->num_rows >0){
    $languageSql    =   $checkLanguage->fetch_assoc();
    $languageId     =   $languageSql['id'];
}else{
    $languageSql    =   $db->query("insert into language(shortName) values('$language')");
    $languageId     =   $db->insert_id;
}
echo $languageId

or second option you add unique constraint to language and shortName .

If you insert a duplicate it will throw an error, if not it will insert, this way you keep only one query the INSERT one, but you might need a try catch for duplicates.

Answer 2

Why not just do something like this:

$language = "en";
$dbh = $db->query("INSERT IGNORE INTO `language` (`shortName`) VALUES ('{$language}');");
$id = $db->insert_id;
echo (($id !== 0) ? $id : FALSE);

This will perform your logic in a single query, and return the id, or false on a duplicate. It is generally better to resolve database performance issues in the SQL rather than in PHP, because about 65% of your overhead is in the actual connection to the database, not the query itself. Reducing the number of queries you run typically has a lot better impact on performance than improving your scripting logic revolving around them. People that consistently rely on ORM's often have a lot of trouble with this, because cookie cutter SQL is usually not very performant.