Why won't this PHP MySQL query work?

Question

I have this as my PHP code:

$username=($_POST['username']);
$password=($_POST['password']);
$query="SELECT * from 'User' WHERE 'Username'='$username'";
mysql_query($query);

if($rows==0)
{
echo"<p> No rows found</p>";
}

else
{

while($row=mysql_fetch_array($query))
{
echo"rows found";
}

}
mysql_close($conn);

And my form code looks like:

<form name="login" action="mydamhlogin.php" method="POST">
<p>Username:<input type="text" name="username"></p>
<p>Password<input type="password" name="password"></p>
<p><input type="submit" value="Login"></p>
</form>

My Database column is called Username and I'm trying to select the rows that match the $username taken from the form but it always returns no rows, but the rows are definitely in the Database.

Answer 1

You are using wrong escape character as single qoutes use backtick operator instead like this

$query="SELECT * from `User` WHERE `Username`='$username'";
$result = mysql_query($query);

Also $rows is empty here you need to do this

$rows = mysql_num_rows($result);

then use this $rows variable to check the value of it.

Answer 2

use this

    $query="SELECT * from `User` WHERE `Username`='$username'";

you shouldnt use single quotes around table and columns , but backticks

also add this

 $rows = mysql_num_rows(mysql_query($query));

before this line

     if($rows==0)

edit:

change this

   while($row=mysql_fetch_array(mysql_query($query)))
   {
   echo $row['username'];   // this if you want output username , if you want something else just write column name
   }

EDIT2.

this is your code

   $username=($_POST['username']);
   $password=($_POST['password']);
   $query=mysql_query("SELECT * from `User` WHERE `Username`='$username'");
   $rows = mysql_num_rows($query);
  if($rows==0)
  {
  echo"<p> No rows found</p>";
 }

 else
{

while($row=mysql_fetch_array($query))
{
echo $row['username'];
}

}
mysql_close($conn);

Answer 3

Here you have missed many issues as $rows is not have any value and $query string. I have modified it use that:

$username=($_POST['username']);
$password=($_POST['password']);
$query="SELECT * from `User` WHERE `Username`='".$username."'";
$exeQuery = mysql_query($query);
$rows = mysql_num_rows($exeQuery)
if($rows==0)
{
echo"<p> No rows found</p>";
} else {

while($row=mysql_fetch_array($exeQuery))
{
echo"rows found";
}

}

Answer 4

$query="SELECT * from User WHERE Username='$username'";
$result=mysql_query($query);

if($result===false) //instead of $rows
...

EDIT:

if( ($result) && (mysql_num_rows($result)>0) )//instead of $rows
...

Answer 5

用这个，

$query="SELECT * from User WHERE `Username`='".$username."'";

Answer 6

查询的语法是错误的尝试这个

$query="SELECT * from User WHERE `Username`='".$username."'";