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连接打开数据库

$mysqli = new mysqli

$mysqli = new mysqli('localhost', 'root', '');
//print_r($mysqli);
$mysqli->select_db('test');

$mysqli = new mysqli();
$mysqli->connect('127.0.0.1', 'root', '',

$mysqli = new mysqli('localhost','root','','test');

得到错误信息

$mysqli->connect_error

$mysqli = @new mysqli('localhost', 'root', '123', 'test');
if ($mysqli->connect_errno) {
    die('Connect Error:' . $mysqli->connect_error);
}

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获取客户端和用户端信息

$mysqli->client_info

$mysqli->server_info

<?php
$mysqli = @new mysqli('localhost', 'root', '', 'test');
echo "客户端的信息：" . $mysqli->client_info . '<br/>';
echo $mysqli->get_client_info() . '<br/>';

echo '客户端的版本: ' . $mysqli->client_version . "<br/>";

echo "服务器端信息：" . $mysqli->server_info . "<br/>";

echo "服务器版本：" . $mysqli->server_version . "<br/>";

?>

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SELECT/DESC/DESCRIBE/SHOW/EXPLAIN执行成功返回mysqli_result对象，执行失败返回false 对于其它SQL语句的执行，执行成功返回true,否则返回false

<?php
$mysqli = @new mysqli('localhost', 'root', '', 'test');
if ($mysqli->connect_errno) {
    die('Connect Error:' . $mysqli->connect_error);
}

$mysqli->set_charset('utf8');

$sql = <<<EOF
    CREATE TABLE IF NOT EXISTS mysqli(
        id TINYINT UNSIGNED AUTO_INCREMENT KEY,
        username VARCHAR(20) NOT NULL
    )
EOF;
$res = $mysqli->query($sql);
var_dump($res);//boolean true

//关闭连接
$mysqli->close();

?>

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