Question

PHP修改数据库问题

<?php

$host = "localhost";
$user = "root";
$pass = "";
$db = "phpdev";

$mysqli = new mysqli($host, $user, $pass, $db);

if (mysqli_connect_errno()) {
die("Unable to connect!");
}
$mysqli->query("SET NAMES 'gbk'");

if (isset($_POST['btnModify'])) {

$sql="UPDATE 'phpdev'.'symbols' SET 'country' = '$_POST[country]','animal' = '$_POST[animal]','cname '='$_POST[cname]' WHERE 'symbols'.'id'' ='$_POST[id]'";
$result=$mysqli->query(sql);
if ($result) {
echo "修改成功";
}else {
echo "修改失败";
}
}

$query = "SELECT * FROM symbols";

if ($result = $mysqli->query($query)) {

if ($result->num_rows > 0) {

echo "<table cellpadding=10 border=1>";
echo "<form method='POST' action=''>";
while($row = $result->fetch_array()) {
echo "<tr>";
echo "<td><input name='id' type='text' id='id' value='$row[0]' /></td>";
echo "<td><input name='country' type='text' id='country' value='$row[1]' /></td>";
echo "<td><input name='animal' type='text' id='animal' value='$row[2]' /></td>";
echo "<td><input name='cname ' type='text' id='cname ' value='$row[3]' /></td>";
echo "<td><input name='bthModify' type='submit' id='bthModify' value='修改' /></td>";
echo "</tr>";
}
echo "</form>";
echo "</table>";
}

$result->close();

}
?>
修改不了数据库内容,高手们帮忙看下是什么原因

Answer 1

你的错误主要在这里
$sql="UPDATE symbols SET country = '$_POST[country]',animal = '$_POST[animal]',cname='$_POST[cname_]' WHERE symbols.id=$_POST[id]";
当存在中文字符时，中文字符用''包围，而英文字符不用，否则会出错的。
像这种symbols.id，句号.只是用于表示指向的，如果是你在单个表中可以把表名省去，就用id就行，只有在多表查询中才需要指明某个字段属于哪个表单。
还有你下面的 $result=$mysqli->query(sql);sql前面应该加一个$。
下面是我改的代码，经过测试可以方便使用：
有个比较怪异的地方是，$_POST[cname_]，它在POST表单中自动添加为cname_，这个是var_dump($_POST)测试的得到的结果，var_dump函数用于查看变量类型以及变量值的。还有后面把表单处改为
echo "<form method='POST' action='{$_SERVER['PHP_SELF']}'>";
actio指向自身，而且将其放在输出循环中，字符集也改为了UTF8，header头先输出声明，否则在IE以为的浏览器中会出现乱码
<?php
header("Content-type: text/html;charset=UTF-8");
$host = "localhost";
$user = "root";
$pass = "";
$db = "phpdev";

$mysqli = new mysqli($host, $user, $pass, $db);

if (mysqli_connect_errno()) {
die("Unable to connect!");
}
$mysqli->query("SET NAMES 'utf8'");

if (isset($_POST['bthModify'])) {
$sql="UPDATE {$db}.symbols SET country = '$_POST[country]',animal = '$_POST[animal]',cname='$_POST[cname_]' WHERE symbols.id=$_POST[id]";
$result=$mysqli->query($sql);
// var_dump($sql);
if ($result) {
echo "修改成功";
}else {
echo "修改失败";
}
}

$query = "SELECT * FROM symbols";

if ($result = $mysqli->query($query)) {

if ($result->num_rows > 0) {

echo "<table cellpadding=10 border=1>";
while($row = $result->fetch_array()) {
echo "<form method='POST' action='{$_SERVER['PHP_SELF']}'>";
echo "<tr>";
echo "<td><input name='id' type='text' id='id' value='$row[0]' /></td>";
echo "<td><input name='country' type='text' id='country' value='$row[1]' /></td>";
echo "<td><input name='animal' type='text' id='animal' value='$row[2]' /></td>";
echo "<td><input name='cname ' type='text' id='cname' value='$row[3]' /></td>";
echo "<td><input name='bthModify' type='submit' id='bthModify' value='修改' /></td>";
echo "</tr>";
echo "</form>";
}
echo "</table>";
}

$result->close();

}
?>

Answer 2

<?php

$host = "localhost";
$user = "root";
$pass = "";
$db = "phpdev";

$mysqli = new mysqli($host, $user, $pass, $db);

if (mysqli_connect_errno()) {
die("Unable to connect!");
}
$mysqli->query("SET NAMES 'gbk'");

if (isset($_POST['btnModify'])) {

$sql="UPDATE symbols SET country= '$_POST[country]',animal= '$_POST[animal]',cname='$_POST[cname]' WHERE id='$_POST[id]'";
$result=$mysqli->query($sql);
if ($result) {
echo "修改成功";
}else {
echo "修改失败";
}
}

$query = "SELECT * FROM symbols";

if ($result = $mysqli->query($query)) {

if ($result->num_rows > 0) {

echo "<table cellpadding=10 border=1>";
echo "<form method='POST' action=''>";
while($row = $result->fetch_array()) {
echo "<tr>";
echo "<td><input name='id' type='text' id='id' value='$row[0]' /></td>";
echo "<td><input name='country' type='text' id='country' value='$row[1]' /></td>";
echo "<td><input name='animal' type='text' id='animal' value='$row[2]' /></td>";
echo "<td><input name='cname ' type='text' id='cname ' value='$row[3]' /></td>";
echo "<td><input name='bthModify' type='submit' id='bthModify' value='修改' /></td>";
echo "</tr>";
}
echo "</form>";
echo "</table>";
}

$result->close();

}
?>

Answer 3

$_POST[id]