连接到数据库性能

Question

我对连接到数据库的效率感兴趣，我是否应该在每个if条件下重新连接到数据库：

if(a > b)
{
    connect to database(mysqli_connect(...,....))
    do some stuff
    close connection to database
}
if(c == d)
{
    connect to database(mysqli_connect(...,....))
    do some stuff
    close connection to database
}

或者以这种方式提高效率：

connect to database(mysqli_connect(...,....))
if(a > b)
{
    do some stuff
}
if(c == d)
{
    do some stuff
}
close connection to database

Answer 1

您应该只打开连接1次，最好只在需要时打开。

$connection = null;

function connect()
{
    if(is_null($connection)) {
        $connection = (mysqli_connect(...,....))
    }
    return $connection;
}

if(a > b)
{
    connect();    
    do some stuff

}
if(c == d)
{
    connect();
    do some stuff
}

if($connection)
    close connection to database