On the php login page, the account password is clearly correct, but the error is always displayed. please take a look. thank you!

$ _ Loginarray (); if (isset ($ _ POST [& #39; submit & #39;]) {$ _ login [& #39; username & #39;] _ check_username ($ _ POST [& #39; zh & #39;], 2, 20); $ _ login [& #39; password & #39;] _ check_password ($ _ POST [& #39; mm & #39;], 6, 18); if (_ fetch_array (& quot; SELECT * FROMuserinforWHERE php

$ _ Login = array ();
If (isset ($ _ POST ['submit ']) {
$ _ Login ['username'] = _ check_username ($ _ POST ['zh '], 2, 20 );
$ _ Login ['password'] = _ check_password ($ _ POST ['mm'], 6, 18 );
If (_ fetch_array ("SELECT * FROM userinfor WHERE username = '{$ _ login ['username']}' and password = '{$ _ login ['password']}' ")) {
Header ("Location: index. php ");
} Else {
Echo "incorrect user name or password ";
}
}

Two functions
Function _ query ($ _ SQL ){
If (! $ Result = mysql_query ($ _ SQL )){
Exit ('SQL execution failed ');
}
Return $ result;
}
Function _ fetch_array ($ _ SQL ){
Return mysql_fetch_array (_ query ($ _ SQL), MYSQL_ASSOC );
}