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PHP introductory tutorial: How to use Mysqli to operate the database (connection, query, transaction rollback, etc.)
PHP introductory tutorial: How to use Mysqli to operate the database (connection, query, transaction rollback, etc.)
The example in this article describes the method of using Mysqli to operate the database in the PHP introductory tutorial. Share it with everyone for your reference, the details are as follows:
Demo1.php
<?php //使用 mysqli 对象操作数据库 //创建 mysqli 对象(资源句柄) $_mysqli = new mysqli(); //连接数据库 1.主机名(ip) 2.账户 3.密码 4.数据库 //mysqli_connect 函数 == $_mysqli -> connect(); $_mysqli -> connect('localhost','root','123456','guest'); //断开 MySQL mysqli_close() == $_mysqli -> close(); $_mysqli -> close(); ?>
Demo2.php
<?php //不用 connect ,直接使用构造方法 $_mysqli = new mysqli('localhost','root','123456','guest'); //单独选择一个数据库 //这里选择的数据库会替代上面的数据库 //为了避免这些麻烦，尽量不用去单独指向了 //$_mysqli -> select_db('school'); $_mysqli -> close(); ?>
Demo3.php
<?php
header ( 'Content-Type:text/html; charset=utf-8;' );
//连接 mysql
//当你参数出现错误，导致连接错误的时候，
//$_mysqli 这个对象就没有创建成功，也就是说，没有资源句柄的功能
//就是没有调用 mysqli 下的方法和属性的能力了
@$_mysqli = new mysqli('localhost','root','123456','guest');
//为什么要用函数去捕捉呢?
//为什么不用面向对象的方式去捕捉呢？
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();
}
$_mysqli->close();
?>
Demo4.php
<?php
header ( 'Content-Type:text/html; charset=utf-8;' );
//连接 mysql
//当你参数出现错误，导致连接错误的时候，
//$_mysqli 这个对象就没有创建成功，也就是说，没有资源句柄的功能
//就是没有调用 mysqli 下的方法和属性的能力了
@$_mysqli = new mysqli('localhost','root','123456','guest');
//为什么要用函数去捕捉呢?
//为什么不用面向对象的方式去捕捉呢？
if(mysqli_connect_errno()){
echo '数据库连接出现了错误，错误的信息是：'.mysqli_connect_error();
exit();
}
//$_mysqli -> select_db('fsdfd');
//数据库操作时发生的错误
if($_mysqli -> errno){
echo '数据库操作错误：'.$_mysqli -> error;
}
$_mysqli->close();
?>
Demo5.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";
//执行 SQL 语句，把结果集赋给 $_result
$_result = $_mysqli -> query($_sql);
//var_dump($_result); //object(mysqli_result)#2 (0) { }
//通过结果集，我要取得第一行数据
//fetch_row();是返回的一个数组，里面是第一条数据的集合
print_r( $_result -> fetch_row());
//运行一次，指针下移一条
print_r( $_result -> fetch_row());
//销毁结果集
$_result -> free();
$_mysqli->close();
?>
Demo6.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);
//使用索引数组取值
//print_r($_result->fetch_row());
$_row = $_result->fetch_row();
echo $_row[3];
//遍历,下标很难记[3]
while (!!$_row = $_result->fetch_row()) {
echo $_row[3].'<br />';
}
$_mysqli->close();
?>
Demo7.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);
//使用关联数组取值
//print_r($_result->fetch_assoc());
$_assoc = $_result->fetch_assoc();
echo $_assoc['tg_username'];
//遍历
while (!!$_assoc = $_result->fetch_assoc()) {
echo $_assoc['tg_username'].'<br />';
}
$_mysqli->close();
?>
Demo8.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);
//使用索引+关联数组取值
//print_r($_result->fetch_array());
$_array = $_result->fetch_array();
echo $_array[3];
echo $_array['tg_username'];
//遍历.....
$_mysqli->close();
?>
Demo9.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);
//使用OOP的方法object
//print_r($_result->fetch_object());
echo $_result->fetch_object()->tg_username;
//使用OOP遍历
while (!!$_object = $_result->fetch_object()) {
echo $_object->tg_username.'<br />';
}
$_mysqli->close();
?>
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();
?>
Demo 13.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();
?>
Demo14.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');
//创建三个修改的SQL语句
$_sql .= "UPDATE tg_article SET tg_username='喀喀喀' WHERE tg_id=1;";
$_sql .= "UPDATE tg_flower SET tg_fromuser='喀喀喀' WHERE tg_id=1;";
$_sql .= "UPDATE tg_friend SET tg_fromuser='喀喀喀' WHERE tg_id=1";
//使用通知执行的方法
$_mysqli->multi_query($_sql);
//普通只能执行sql的方法是:$_mysqli->query($_sql);
$_mysqli->close();
?>
Demo15.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');
//创建三条选择语句
$_sql .= "SELECT * FROM tg_photo;";
$_sql .= "SELECT * FROM tg_user;";
$_sql .= "SELECT * FROM tg_friend";
if ($_mysqli->multi_query($_sql)) {
//获取当前的结果集
$_result = $_mysqli->store_result();
print_r($_result->fetch_row());
echo '<br />';
//将结果集的指针移到下一条
$_mysqli->next_result();
$_result = $_mysqli->store_result();
if (!$_result) {
echo '第二条SQL语句有五!';
exit();
}
print_r($_result->fetch_row());
echo '<br />';
$_mysqli->next_result();
$_result = $_mysqli->store_result();
if (!$_result) {
echo '第三条SQL语句有五!';
exit();
}
print_r($_result->fetch_row());
} else {
echo '第一条SQL语句有误';
exit();
}
$_mysqli->close();
?>
Demo16.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');
//设置关闭自动提交(手工提交)
$_mysqli->autocommit(false);
//创建两个SQL语句
$_sql .= "UPDATE tg_flower SET tg_flower=tg_flower-50 WHERE tg_id=1;";
$_sql .= "UPDATE tg_friend SET tg_state=tg_state+50 WHERE tg_id=1";
//执行多条SQL语句
//只要这两条SQL语句都成功了，就手工提交给数据库
//否则，就回滚，撤销之前的有效操作。
if ($_mysqli->multi_query($_sql)) {
//通过影响的行数，来判定SQL语句是否成功执行
//如果$_success是false说明sql语句有吴，那么就执行回滚，否则就手工提交
$_success = $_mysqli->affected_rows == 1 ? true : false;
//下移指针
$_mysqli->next_result();
$_success2 = $_mysqli->affected_rows == 1 ? true : false;
//如果两条都成功的话
if ($_success && $_success2) {
//执行手工提交
$_mysqli->commit();
echo '完美提交';
} else {
//执行回滚，撤销之前的所有操作
$_mysqli->rollback();
echo '所有操作归零！';
}
} else {
echo '第一条SQL语句有错误!';
}
//再开启自动提交
$_mysqli->autocommit(true);
$_mysqli->close();
?>
I hope this article will be helpful to everyone in PHP program design.
For more PHP introductory tutorials on how to use Mysqli to operate the database (connection, query, transaction rollback, etc.) and related articles, please pay attention to the PHP Chinese website!
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