PHP与MySQL（15）

PHP配置

extension_dir = "ext"
extension=php_mysqli.dll

建立和断开链接

$mysqli = new mysqli();//实例化mysqli类
$mysqli -> connect("localhost","root","123");//链接数据库
$mysqli -> select_db("text");//选择text数据库
$mysqli -> close();//关闭链接

获取错误信息

• 获取错误码

$mysqli = new mysqli("localhost","root","123","test");
echo $mysqli -> errno;//没有错误返回0

• 获取错误信息

$mysqli = new mysqli("localhost","root","123");//实例化mysqli类
$mysqli -> select_db("text");//选择text数据库
if($mysqli -> errno){
echo $mysqli -> error;//Unknown database 'text' 没有text数据库
}
$mysqli -> close();//关闭链接

• 在单独的文件中存储链接信息

//mysql.connect.php文件
<?php
$mysqli = new mysqli("localhost","root","123","test");
?>

• 在必要时包含此文件

<?php
include "mysql.connect.php";//调用mysql.connect.php文件
?>

与数据库交互

获取数据

$mysqli = new mysqli("localhost","root","123","test");
$query = "select id, name, age from xiu";
$result = $mysqli -> query($query,MYSQLI_STORE_RESULT);
while(list($id,$name,$age) = $result -> fetch_row()){
printf("%d*%d*%d",$id,$name,$age);
}
$mysqli -> close();

插入、删除或更新数据

$mysqli = new mysqli("localhost","root","123","test");
$query = "alter table xiu add column birdate date";
$result = $mysqli -> query($query);
echo $mysqli -> affected_rows;
$mysqli -> close();

释放查询内存

解析查询结果