php数据访问（修改）

修改：跟添加相似，需要显示默认值

先嵌入php代码  查询数据库

$code = $_GET["c"];

$db = new MySQLi("localhost","root","159357","renyuanxinxi");

$ainfo = "select * from info where code='{$code}'";

$binfo = $db->query($ainfo);

$cinfo = $binfo->fetch_row();

在网页中显示所查询的值（在表单中嵌入相应的简短php代码，进行赋值设定）

<form action="xiugaichuli.php" method="post">
    <div><input type="hidden" name="code" value="<?php echo $ainfo[0]; ?>" /></div>
    <div>姓名：<input type="text" name="name" value="<?php echo $ainfo[1]; ?>" /></div>
    
    
    
    <div>性别：                           //true   false判定
    <input type="radio" name="sex" value="1" <?php echo $ainfo[2]?"checked='checked'":"" ?> />男
    &nbsp;
    <input type="radio" name="sex" value="0" <?php echo $ainfo[2]?"":"checked='checked'" ?> />女
    </div>
    
    
    
    <div>民族：
    <select name="nation">
        <?php
        
        $sql = "select * from nation";
        $result = $db->query($sql);
        $attr = $result->fetch_all();
        
        foreach($attr as $v)               //下拉列表设默认
        {
            if($v[0]==$ainfo[3])
            {
                echo "<option selected='selected' value='{$v[0]}'>{$v[1]}</option>";
            }
            else
            {
                echo "<option value='{$v[0]}'>{$v[1]}</option>";
            }
        }
        ?>
    </select>
    </div>
    
    
    
    <div>生日：<input type="text" name="birthday" value="<?php echo $ainfo[4]; ?>" /></div>
    
    <div><input type="submit" value="修改" /></div>
</form>        

建立修改处理页面（先取值、再用修改语句 根据主键值 选择所要修改的列、然后再执行）

<?php

$code = $_POST["code"];                         //取值
$name = $_POST["name"];
$sex = $_POST["sex"];
$nation = $_POST["nation"];
$birthday = $_POST["birthday"];


$db = new MySQLi("localhost","root","159357","renyuanxinxi");

$sql = "update info set name='{$name}',sex={$sex},nation='{$nation}',birthday='{$birthday}' where code='{$code}'";//用修改语句 根据主键值 选择所要修改的列

$db->query($sql);                 //执行

header("location:main.php");