php 检查 SQL 数据库是否存在值，如果存在则返回值
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Check SQL database if value exists and then return value if it does
提问by Jamie Fritz
I am pretty new to both php and SQL. I have a login page where I ask for the users username and password. I would like to search a database I have created for both the username and password to see if they exist. The database table has two columns, Username and Password. I don't care to much about security so a simple script will work. But I do want to be able to expand on it someday, so therefor I am using a database, because currently I just use an array in php to store usernames and passwords.
我对 php 和 SQL 都很陌生。我有一个登录页面，我在其中询问用户的用户名和密码。我想搜索我为用户名和密码创建的数据库，看看它们是否存在。数据库表有两列，用户名和密码。我不太关心安全性，所以一个简单的脚本就可以工作。但我确实希望有一天能够扩展它，因此我使用了一个数据库，因为目前我只是在 php 中使用一个数组来存储用户名和密码。
I am currently trying to get this code to work but am not getting the results I need.
我目前正在尝试让这段代码工作，但没有得到我需要的结果。
$user_name = "db_username";
$password = "db_password";
$database = "db_name";
$server = "db_server";
$db_handle = mysql_connect($server, $user_name, $password);
$db_found = mysql_select_db($database, $db_handle);
if ($db_found) {
$result =mysql_query("SELECT 1 FROM my_table WHERE Username = $username");
if ($result>0)
{
echo 'Username and Password Found';
}
else
{
echo 'Username and Password NOT Found';
}
}
else {
print "Database NOT Found.";
mysql_close($db_handle);
}
This always returns Username and Password Foundno matter is the username is in there or not. When printing $resultI get Resource id #2. Thank you
Username and Password Found无论用户名是否在那里，这总是会返回。打印时$result我得到Resource id #2. 谢谢
回答by Buttle Butkus
$result I think will evaluate to true even if the result set contains zero rows. It only returns boolean false on error according to the manual. Use mysql_num_rows to determine if you actually found anything with the query.
$result 我认为即使结果集包含零行也会评估为真。根据手册，它只在错误时返回布尔假。使用 mysql_num_rows 确定您是否真的通过查询找到了任何内容。
if ($db_found) {
$result =mysql_query("SELECT 1 FROM my_table WHERE `Username` = '$username'");
if ($result && mysql_num_rows($result) > 0)
{
echo 'Username and Password Found';
}
else
{
echo 'Username and Password NOT Found';
}
}
else {
print "Database NOT Found.";
mysql_close($db_handle);
}
EDIT: Of course, as of now (November 2013, and since long ago), the mysql_* functions have indeed been deprecated. Apparently you can now use identical mysqli_* functions (maybe just use find/replace), but most people are using PDO.
编辑：当然，截至目前（2013 年 11 月，以及很久以前），mysql_* 函数确实已被弃用。显然，您现在可以使用相同的 mysqli_* 函数（也许只使用查找/替换），但大多数人都在使用 PDO。
回答by Mike Purcell
回答by user3429291
<?php
$user=$_POST["user"];
$pass=$_POST["pass"];
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "interior_design";
$db_handle = mysql_connect($servername,$username,$password);
$db_found = mysql_select_db($dbname,$db_handle);
if($db_found)
{
$result = mysql_query("SELECT ssn,fname FROM admin WHERE ssn='$pass' and fname='$user'");
if ($result && mysql_num_rows($result) > 0)
{
echo 'Username and Password Found';
//header( 'Location: index.html' ) ;
}
else
{
echo 'Username and Password NOT Found';
echo $pass;
echo $user;``
}
}
else{
echo 'db nt found';
mysql_close($db_hanle);
}
?>
<html>
<body>
<a href="login.html"><h2>LOGIN</h2></a>
</body>
</html>
