php如何实现数据库的增删改查

1 查询: 数据的显示,这里就可以嵌入php来进行数据的输出

1.查询:

数据的显示,这里就可以嵌入php来进行数据的输出

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <title>无标题文档</title>
</head>

<body>
<table width="100%" border="1" cellpadding="0" cellspacing="0">
  <tr>
    <td>代号</td>
    <td>名称</td>
    <td>性别</td>
    <td>生日</td>
    <td>班级</td>
    <td>操作</td>
  </tr>

<?php
$db = new MySQLi("localhost","root","12345678","heiheihei");
//连接数据库
$sql = "select * from student ";
//写sql语句
$r = $db->query($sql);
//执行sql语句返回给r
if($r)//条件
{
  while ($attr = $r->fetch_row())
  {
    $ssex = "";
     if($attr[2])
     {
       $ssex = "男";
     }
     else
       {
         $ssex = "女";
       }
    echo
    "
 <tr>
    <td>{$attr[0]}</td>
    <td>{$attr[1]}</td>
    <td>{$ssex}</td>
    <td>{$attr[3]}</td>
    <td>{$attr[4]}</td>
//添加一个单击事件,防止不小心删掉
<td><a onclick=\"return confirm('确定要删除吗???')" 
href='shanchu.php?sno={$attr[0]}'>删除</a>
 <a href='xiugai.php?sno={$attr[0]}'>修改</a> </td> </tr>"; } } ?>

 
 

</table>
<a href="tianjia.php" rel="external nofollow" >添加页面</a>
</body>

</html>

2.删除的处理页面

删除时是链接到删除处理页面的,所以还要写一个删除处理页面:

<?php
$aaa = $_GET ["sno"]; //删除方式使用的get,照旧
$db = new mysqli("localhost","root","12345678","heiheihei");
//连接...
$sql = "delete from student WHERE sno='{$aaa}'";
//写sql语句,sno主键
if($db->query($sql)) //执行sql语句
{
  header("location:text.php");
//删完回去表页面
}
else{
  echo "删除失败";
}
?>

来张效果图:

3.添加数据:

点击即可进入添加页面

添加页面:

<body>

<h1>添加</h1>
<form action="add.php" method="post" >
  <div>代号:<input type="text" name="sno"/></div>
  <div>名字:<input type="text" name="sname"/></div>
  <div>性别: <input type="radio" value="1" name="sex" />男
    <input type="radio" value="0" name="sex"/>女</div>
  <div>日期:<input type="text" name="sbirthday"/></div>
//创建表时性别是用的1或2来表示的,要是进行修改不知道1或2代表了什么,所以就要进行处理,处理成用户能够明白的男和女

  <div>班级:
  <select name="class">

  <?php
    $db= new MYSQLi("localhost","root","12345678","heiheihei");
//连接...
    $sql = " select * from class ";
//写sql...    

    $r = $db->query($sql);
//执行...返回...
    while($arr = $r->fetch_row())
    {
      echo "<option value='{$arr[0]}'>{$arr[1]}</option>";
      //添上以后回表页面
    }
    ?>

 
  </select>
  </div>
  <div><input type="submit" value="添加"/></div>
</form>

</body>

添加也需要一个处理页面来判断添加:

<?php
$sno = $_POST["sno"];
//$_POST 变量用于收集来自 method="post" 的表单中的值。
$sname = $_POST["sname"];
$ssex = $_POST["ssex"];
$sbirthday = $_POST["sbirthday"];
$class = $_POST["class"];
$db = new mysqli("localhost","root","12345678","heiheihei");
$sql = "insert into student VALUES ('{$sno}','{$sname}','{$ssex}','{$sbirthday}','{$class}')";
//向数据库中添加写的数据
  if($db->query($sql))
{
  header("location:text.php");
  //header() 函数向客户端发送原始的 HTTP 报头。
}
else {
  echo "添加失败";
}


?>

效果图:

4.修改数据:主键不可修改!!

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <title>无标题文档</title>
</head>

<body>

<h1>修改</h1>

<?php
$sno = $_GET{"sno"};
$db = new mysqli("localhost","root","12345678","heiheihei");
$sql = "select * from student WHERE sno='{$sno}'";
$r = $db->query($sql);
$arr = $r->fetch_row();
?>

 
<form action="update.php" method="post">
  <div>代号:<input readonly="readonly" type="text" name="sno" value="<?php
echo $arr[0];
?>"/></div>

//readonly只可读
 <div>名称:<input type="text" name="sname" value="<?php echo $arr[1]; ?>"/></div> <div>性别: <input type="radio" name="ssex" value="1" <?php echo $arr[2]?"checked='checked'":""; ?>/>男 <!-- 三元运算符,如果性别=ture,默认值就在男上面,否则空--> <input type="radio" name="ssex" value="0" <?php echo $arr[2]?"":"checked='checked'"; ?>/>女 </div> <div>日期:<input type="text" name="sbirthday" value="<?php echo $arr[3]; ?>"/></div> <div>班级:<select name="class">
//value取默认值
 

 <?php
      $sclass = "select * from class";
      $rclass = $db->query($sclass);
      while($attr = $rclass->fetch_row())
      //取到的班级信息
      {
        //判断将要输出的班级是不是和该人员的是否相同
        if($arr[4]==$attr[0])//arr是班级名,attr是班级的代号,俩表
        {
          echo "<option value = '{$attr[0]}' selected='selected'>{$attr[1]}</option>";

        }
        else{
          echo "<option value = '{$attr[0]}'>{$attr[1]}</option>";
        }

      }
      ?>

 
    </select></div>
  <div><input type="submit" value="修改完毕"/></div>

</form>


</body>
</html>

]

修改的处理页面:

<?php
$sno = $_POST["sno"];
$sname = $_POST["sname"];
$ssex = $_POST["ssex"];
$sbirthday = $_POST["sbirthday"];
$class = $_POST["class"];
$db = new mysqli("localhost","root","12345678","heiheihei");
$sql = "update student set sname='{$sname}',
ssex='{$ssex}',
sbirthday='{$sbirthday}',
class='{$class}' WHERE sno='{$sno}'";
//看一下是不是传递过来的sno值;
if($db->query($sql))
{
  header("location:text.php");
}
else{
  echo "修改失败";
}



?>

修改的效果图:

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