mysql vs mysqli config file and queries

问题

I need start using the mysqli extension but I'm finding all kinds of conflicting info depending on how all the info is that I'm trying to use.

For example, my header connects to a 'config.php' file that currently looks like this:

<?php
$hostname_em = "localhost";
$database_em = "test";
$username_em = "user";
$password_em = "pass";
$em = mysql_pconnect($hostname_em, $username_em, $password_em) or trigger_error(mysql_error(),E_USER_ERROR); 
?>

But when I go to php.net I see that I should be using this but after updating everything I get no database.

<?php
$mysqli = new mysqli("localhost", "user", "password", "database");
if ($mysqli->connect_errno) {
echo "Failed to connect to MySQL: (" . $mysqli->connect_errno . ") " . $mysqli->connect_error;
}
echo $mysqli->host_info . "\n";

$mysqli = new mysqli("127.0.0.1", "user", "password", "database", 3306);
if ($mysqli->connect_errno) {
echo "Failed to connect to MySQL: (" . $mysqli->connect_errno . ") " . $mysqli->connect_error;
}

echo $mysqli->host_info . "\n";
?>

I also went through and added an "i" to the following code in my site and again no luck:

mysql_select_db($database_em, $em);
$query_getReview =
"SELECT 
reviews.title,
reviews.cover_art,
reviews.blog_entry,
reviews.rating,
reviews.published,
reviews.updated,
artists.artists_name,
contributors.contributors_name,
contributors.contributors_photo,
contributors.contributors_popup,
categories_name
FROM
reviews
JOIN artists ON artists.id = reviews.artistid
JOIN contributors ON contributors.id = reviews.contributorid
JOIN categories ON categories.id = reviews.categoryid
ORDER BY reviews.updated DESC LIMIT 3";
$getReview = mysql_query($query_getReview, $em) or die(mysql_error());
$row_getReview = mysql_fetch_assoc($getReview);
$totalRows_getReview = mysql_num_rows($getReview);

And here's the only place on my display page that even mentions mysql so far:

<?php } while ($row_getReview = mysql_fetch_assoc($getReview)); ?>

I did see something at oracle that another stackoverflow answer pointed someone to that updates this stuff automagically, but I have so little code at this point it seems like overkill.

回答1:

Adding an i to any mysql function won't make it a valid mysqli function. Even if such function exists, maybe the parameteres are different. Take a look here http://php.net/manual/en/book.mysqli.php and take some time to check mysqli functions. Maybe try some examples to become familiar with the way things work. I also reccomend you to choose either object oriented code, either procedural. Don't mix them.

回答2:

I just made the switch to mysqli lately, took me a few hours to wrap my head around it. It works well for me, hope it will help you out a bit.

Here the function to connect to the BD:

function sql_conn(){
    $sql_host = "localhost";
    $sql_user = "test";
    $sql_pass = "pass";
    $sql_name = "test";
    $sql_conn = new mysqli($sql_host, $sql_user, $sql_pass, $sql_name);
    if ($sql_conn->connect_errno) error_log ("Failed to connect to MySQL: (" . $sql_conn->connect_errno . ") " . $sql_conn->connect_error);
    return $sql_conn;
}

This will return a Mysqli Object that you can use to make you request afterward. You can put it in your config.php and include it or add it at the top of your file, whatever works the best for you.

Once you have this object, you can use it to make your query against the object like so: (in this case, if an error came up it will be outputted in the error_log. I like having it there, you can echo it instead.

    //Use the above function to create the mysqli object.
    var $mysqli = sql_conn();

    //Create the query string (truncated for the example)
    var $query = "SELECT reviews.titl ... ... ted DESC LIMIT 3";

    //Launch the query on the mysqli object using the query() method
    if(!($results = $mysqli->query($query))){
        //It it fails, log the error

        error_log(mysqli_error($mysqli));
    }else{
        //Manipulate your data.
        //here it depends on what you retunr, a single value, row or a list of rows.
        //Example for a set of rows

        while ($record = $results->fetch_object()){ 
          array_push($array, $record); 
        }
    }
   //Just to show, this will output the array:
   print_r($array);

  //Close the connection:
  $mysqli->close();

So basically, in mysqli, you create an object and use the method to work your way out. Hope this helps. Once you figured it out, you will most likely enjoy mysqli more that mysql. I did anyway.

PS: Please note that this was copy/pasted from existing, working code. Might have some typo, and might forgot to change a var somewhere, but it's to give you an idea of how mysqli works. Hope this helps.

来源：https://stackoverflow.com/questions/13633680/mysql-vs-mysqli-config-file-and-queries

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