PHP入门教程之使用Mysqli操作数据库的方法(连接,查询,事务回滚等

2019-05-03 02:27:33王振洲

Demo10.php

<?php
  header ( 'Content-Type:text/html; charset=utf-8;' );
  $_mysqli = new mysqli('localhost','root','123456','testguest');
  //数据库连接时发生的错误
  if (mysqli_connect_errno()) {
    echo '数据库连接出现了错误.错误的信息是:'.mysqli_connect_error();
    exit();
  }
  //设置一下编码
  $_mysqli->set_charset('utf8');
  //创建一句SQL,获取数据库的表的数据
  $_sql = "SELECT * FROM tg_user limit 0,10";
  //创建一个结果集
  $_result = $_mysqli->query($_sql);
  //我要看下我选择了多少行
  echo $_result->num_rows;
  //我影响了多少行呢
  echo $_mysqli->affected_rows;
  $_mysqli->close();
?>

Demo11.php

<?php
  header ( 'Content-Type:text/html; charset=utf-8;' );
  $_mysqli = new mysqli('localhost','root','123456','testguest');
  //数据库连接时发生的错误
  if (mysqli_connect_errno()) {
    echo '数据库连接出现了错误.错误的信息是:'.mysqli_connect_error();
    exit();
  }
  //设置一下编码
  $_mysqli->set_charset('utf8');
  //创建一句SQL,获取数据库的表的数据
  $_sql = "UPDATE tg_user SET tg_username='一站式建网站' WHERE tg_id=5";
  //创建一个结果集
  $_result = $_mysqli->query($_sql);
  //我要看下我选择了多少行
  echo $_result->num_rows;
  echo '|';
  //我影响了多少行呢
  echo $_mysqli->affected_rows;
  $_mysqli->close();
?>

Demo12.php

<?php
  header ( 'Content-Type:text/html; charset=utf-8;' );
  $_mysqli = new mysqli('localhost','root','123456','testguest');
  //数据库连接时发生的错误
  if (mysqli_connect_errno()) {
    echo '数据库连接出现了错误.错误的信息是:'.mysqli_connect_error();
    exit();
  }
  //设置一下编码
  $_mysqli->set_charset('utf8');
  //创建一句SQL,获取数据库的表的数据
  $_sql = "SELECT * FROM tg_user";
  //创建一个结果集
  $_result = $_mysqli->query($_sql);
  //求出表中有多少个字段
  echo $_result->field_count;
  //获取字段的名字
// $_field = $_result->fetch_field();
// echo $_field->name;
// $_field = $_result->fetch_field();
// echo $_field->name;
//
// while (!!$_field = $_result->fetch_field()) {
//   echo $_field->name.'<br />';
// }
  //一次性取得所有的字段
  $_fields = $_result->fetch_fields();
  //echo $_fields[0]->name;
  foreach ($_fields as $_field) {
    echo $_field->name.'<br />';
  }
  $_mysqli->close();
?>

Demo13.php

<?php
  header ( 'Content-Type:text/html; charset=utf-8;' );
  $_mysqli = new mysqli('localhost','root','123456','testguest');
  //数据库连接时发生的错误
  if (mysqli_connect_errno()) {
    echo '数据库连接出现了错误.错误的信息是:'.mysqli_connect_error();
    exit();
  }
  //设置一下编码
  $_mysqli->set_charset('utf8');
  //创建一句SQL,获取数据库的表的数据
  $_sql = "SELECT * FROM tg_user";
  //创建一个结果集
  $_result = $_mysqli->query($_sql);
  //移动数据指针
  $_result->data_seek(9);
  $_row = $_result->fetch_row();
  echo $_row[3];
  //移动字段指针
  $_result->field_seek(3);
  $_field = $_result->fetch_field();
  echo $_field->name;
  $_mysqli->close();
?>

								 
			 
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