关于PHP数据库mysql的一些案例

案例1：查询select

使用php连接数据库class9,

获取数据库的表student中的信息，

然后输出到页面上（用表格套住）

 <?php
 header("Content-type:text/html; charset=utf-8");
 // 建立mysql的链接
 // 参数：主机名，用户，密码，需要的数据库
 /*
 在PHP函数方法前面加@符号，表示忽略警告
 */
 $conn =@mysqli_connect("localhost","root","","lanou0322");
 // 判断数据库链接是否成功
 /*if($conn){
 echo "成功了!";
 }else{
 echo "失败了!";
 }
 */
 if(!$conn){
 echo "失败";
 // 终止
 exit;
 }
 $conn->query('set names utf8');
 $sql ="SELECT * FROM student";
 $result = $conn->query($sql);
 // 5.判断
 // mysqli_num_rows 返回的条数
 // echo mysqli_num_rows($result);
 if(mysqli_num_rows($result)>0){
 echo "<table border=1>";
 echo "<tr>
 <th>id</th>
 <th>name</th>
 <th>sex</th>
 <th>age</th>
 </tr>";
 while($row = $result -> fetch_assoc()){
 echo "<tr>
 <td style='width:20'>{$row['id']}</td>
 <td style='width:80; text-align:center;'>{$row['name']}</td>
 <td style='width:20'>{$row['sex']}</td>
 <td style='width:20'>{$row['age']}</td>
 </tr>";
 }
 echo "</table>";
 //如果想在一个页面输出同样的两个数据库表格那么可以在执行一次$conn->query($sql);然后打印
 echo "<hr/>";
 $result = $conn->query($sql);
 echo "<table border=1>";
 echo "<tr>
 <th>id</th>
 <th>name</th>
 <th>sex</th>
 <th>age</th>
 </tr>";
 while($row = $result -> fetch_assoc()){
 echo "<tr>
 <td style='width:20'>{$row['id']}</td>
 <td style='width:80; text-align:center;'>{$row['name']}</td>
 <td style='width:20'>{$row['sex']}</td>
 <td style='width:20'>{$row['age']}</td>
 </tr>";
 }
 echo "</table>";
 }
 // 关闭数据库
 $conn->close();//关闭数据库

 ?>

效果：

案例2：插入insert

使用php连接数据库

1. 向数据表student,插入一条信息："小明", 28, "男"   添加成功输出提示"添加成功"

 

2. 插入多条信息

 <?php
 header("Content-type:text/html;charset=utf-8");
 //链接数据库
 $conn =@mysqli_connect("localhost","root","","lanou0322");
 if(!$conn){
 echo "失败";
 // 终止
 exit;
 }
 $conn->query('set names utf8');
 //向数据库添加数据INSERT INTO name(数据表名) VALUE （添加的数据信息）;
 $sql ="INSERT INTO student(name,sex,age) VALUES ('小黄','女','17')";
 $sql ="SELECT * FROM student";
 $result = $conn->query($sql);
 // 判断插入是否成功
 // 使用 mysqli_affected_rows($conn);
 if(mysqli_affected_rows($conn)>0){
 echo "成功";
 }else{
 echo "失败";
 }
 echo mysqli_num_rows($result);
 if(mysqli_num_rows($result)>0){
 echo "<table border=1>";
 echo "<tr>
 <th>id</th>
 <th>name</th>
 <th>sex</th>
 <th>age</th>
 </tr>";
 while($row = $result -> fetch_assoc()){
 echo "<tr>
 <td style='width:20'>{$row['id']}</td>
 <td style='width:80; text-align:center;'>{$row['name']}</td>
 <td style='width:20'>{$row['sex']}</td>
 <td style='width:20'>{$row['age']}</td>
 </tr>";
 }
 echo "</table>";
 }
     $conn->close();//关闭数据库
 ?>

效果：

案例3：更新update

使用php连接数据库

更新(修改)数据表student中，年龄age=28的改为10

 <?php
 header("Content-type:text/html;charset=utf-8");
 $conn =@mysqli_connect("localhost","root","","lanou0322");
 $conn->query('set names utf8');
 // mysqli_query($conn,"UPDATA name SET... WHERE ...")
 $sql = mysqli_query($conn,"UPDATE student SET name = '我傻逼',age = '10' WHERE id = 1");
 $sql ="SELECT * FROM student";
 $result = $conn->query($sql);
 echo mysqli_affected_rows($conn);
 // 判断修改是否成功
 if(mysqli_affected_rows($conn)>0){
 echo "成功";
 }else{
 echo "失败";
 }
 echo mysqli_num_rows($result);
 if(mysqli_num_rows($result)>0){
 echo "<table border=1>";
 echo "<tr>
 <th>id</th>
 <th>name</th>
 <th>sex</th>
 <th>age</th>
 </tr>";
 while($row = $result -> fetch_assoc()){
 echo "<tr>
 <td style='width:20'>{$row['id']}</td>
 <td style='width:80; text-align:center;'>{$row['name']}</td>
 <td style='width:20'>{$row['sex']}</td>
 <td style='width:20'>{$row['age']}</td>
 </tr>";
 }
 echo "</table>";
 }
 $conn->close();
 ?>

效果：

案例4：删除delete

使用php连接数据库class9,

删除数据库的表student中，id号为1的数据

 <?php
 header("Content-type:text/html;charset=utf-8");
 $conn =@mysqli_connect("localhost","root","","lanou0322");
 $conn->query('set names utf8');
 $sql = mysqli_query($conn,"DELETE FROM student WHERE id = 1");
 $sql ="SELECT * FROM student";
 $result = $conn->query($sql);
 // echo mysqli_affected_rows($conn);
 // 判断修改是否成功
 if(mysqli_affected_rows($conn)>0){
 echo "成功";
 }else{
 echo "失败";
 }
 // echo mysqli_num_rows($result);
 if(mysqli_num_rows($result)>0){
 echo "<table border=1>";
 echo "<tr>
 <th>id</th>
 <th>name</th>
 <th>sex</th>
 <th>age</th>
 </tr>";
 while($row = $result -> fetch_assoc()){
 echo "<tr>
 <td style='width:20'>{$row['id']}</td>
 <td style='width:80; text-align:center;'>{$row['name']}</td>
 <td style='width:20'>{$row['sex']}</td>
 <td style='width:20'>{$row['age']}</td>
 </tr>";
 }
 echo "</table>";
 }
 $conn->close();
 ?>

效果：