php连接mysql数据库

步骤

• 连接数据库

       $link = mysqli_connect('localhost','root','123456');

• 判断/返回连接状态

       if(!$link){

       echo "不儿，tm卧槽～数据库连接失败";

}

• 设置连接字符集

      mysqli_set_charset($link,'utf8')

• 选择数据库

     mysqli_select_db($link,'warmwinterI')

• 准备sql语句

     $sql = "select * from mycoachinfo"

• 发送sql语句

     $res = mysqli_query($link,$sql)

• 处理结果集

     $result = mysqli_fetch_assoc($res)//返回值是关联数组，执行一次，往下读一行

　  var_dump($result)

• 关闭数据库释放资源

     mysqli_close($link)

 综合演练

<?php
  $link = mysqli_connect('127.0.0.1','root','wenwajiao'); //注意，主机域名务必写为127.0.0.1如果是localhost肯定会出幺蛾子！！！
 
 if ($link)
 {
     mysqli_set_charset($link,'utf8');
     mysqli_select_db($link,"oldpassion");
     $sql =  "select * from loginfo";
     $res = mysqli_query($link,$sql);
     while($rows = mysqli_fetch_assoc($res)){
        var_dump($rows);
        echo "<br/>";   
   }
 };

 $sql2 = "select * from loginfo";
 $res = mysqli_query($link,$sql2);
 $count= mysqli_num_rows($res);
 echo $count."<br/>";
 echo "上面是关联数组"."<br/>";
 echo "==============================="."<br/>";
 echo "下面是索引关联数组"."<br/>";
 while($workout = mysqli_fetch_array($res))
 {
     var_dump($workout);
   echo "<br/>";
 }
?>

• mysqli_num_rows//返回查询的行数
• mysqli_fetch_array//返回一个既有索引又有关联的数组

• mysqli_affected_rows//返回删除，修改等操作受影响的行数

<?php
$link=mysqli_connect('127.0.0.1','root','wenwajiao');
if ($link)
{
    mysqli_set_charset($link,'utf8');
    mysqli_select_db($link,'oldpassion');
    $sql2 = "insert into loginfo values(4, 'xxd','徐晓冬','xxd')";
    $res = mysqli_query($link,$sql2);
    $duwa = mysqli_affected_rows($link);
    echo $duwa."<br/>"; 
}
?>

• mysqli_insert_id//返回自增主键的值

<?php
$link=mysqli_connect('127.0.0.1','root','wenwajiao');

if ($link)
{
    mysqli_set_charset($link,'utf8');
    mysqli_select_db($link,'oldpassion');
    $id = mysqli_insert_id($link);
    echo $id;
    $sql2 = "insert into loginfo values(4, 'xxd','徐晓冬','xxd')";
    echo mysqli_insert_id($link)."<br/>";
    $res = mysqli_query($link,$sql2);
    $duwa = mysqli_affected_rows($link);
    echo $duwa."<br/>"; 
}

?>