PHP中管理数据库的一些操作

以下的方法都是在面向对象连接数据库的基础上

1.执行SQL查询（预定义）
$sql_check = “SELECT * FROM users WHERE username = ?”;
$stmt = $link->prepare($sql_check);
$stmt->bin{d}_{p}aram{(}^{\prime }{s}^{\prime },$username);
$stmt->execute();
$stmt->store_result();
$stmt->bin{d}_{r}esult($qq,$use{r}_{n}ame,$pass_word);
if($stmt->fetch()){
$stmt->free_result();
echo “用户名已存在，试试其他的吧”;
exit();
}
$stmt->free_result();

2.执行SQL查询（存储在数组里）
$query = “SELECT productid, name, price FROM product ORDER BY name”;
$result = $mysqli->query($query);
while ($row = $result->fetch_object())
{
$name = $row->name;
$productid = $row->productid;
$price = $row->price;echo"($productid) $name: $price
";
}

3.执行SQL插入
$sql="INSERTINTOusersVALUES($password,'$usernam{e}^{\prime },$password)";
if ($link->query($sql) === TRUE) {
echo “新记录插入成功
”;
KaTeX parse error: Expected 'EOF', got '}' at position 73: …=index.html"); }̲ else { ech…link->error;
$link->close();
exit();
}

4.执行SQL删除
$results = $mysqli->query(“DELETE FROM products WHERE products = 1”);

if($results){
print ‘删除成功’;
}else{
print ‘删除失败Error:(’. $mysqli->errno .’)’;
}

5.执行SQL更新
$sq{l}_{r}eset="UPDATEusersSETpassword=$password,qq=$passwordWHEREusername{=}^{\prime }$username’";
$result = $link->query($sql_reset);
if($result){
echo “修改成功!
”;
echo “3秒后返回登入页面！”;
$link->close();
header(“refresh:3;url=index.html”);
}else{
echo “由于不明原因修改失败”;
exit();
}