Mysql

comment resoudre un probleme de type "Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given in C:\Program Files\EasyPHP-5.3.6.0\www\www\projet1\racine\pages\affich.php on line 25"
voici le code complet

<table border="2" cellpadding="5" width="95%" align="center" bordercolor="#000000" cellspacing="0">
<tr>
<td colspan="2" align="center">
<b><font size="10">INSCRITS DU JOUR <br />
<?php
include("./codes/datejour.php");
?>
</font></b>
</td>
</tr>
<tr>
<td align="center"><b><font size="3">DE 6H A 12H</font></b></td>
<td align="center"><b><font size="3">DE 12H A 18H</font></b></td>
</tr>
<tr>
<td>
<?php
$ds=date("Y-m-d");
$sh="06:00:00";
$dh="12:00:00";
$hh="18:00:00";
include("./codes/connexion.php");
$req1="SELECT*FROM student where dateinscrit='$ds' and heureinscrit>=$sh and heureinscrit<$hh order by id desc";
$env1=mysql_query($req1);
$num1=mysql_num_rows($env1);
if($num1!=0)
{
while($recup1=mysql_fetch_assoc($env1))
{
$nom1=strtouper($recup1["nom"]);
$prenom1=UCwords($recup1["prenom"]);
$sexe1=$recup1["sexe"];
$datenaiss1=$recup1["datenaiss"];
$lieunaiss1=UCfirst($recup1["Lieunaiss1"]);
$cel1=$recup1["cel"];
$tel1=$recup1["tel"];
$mail1=strtolower($recup1["email"]);
$hinscrit1=$recup1["heureinscri"];
if($sexe1=="M")
{
$sig1="Mr";
$col="blue";
$naiss1="Né le ";
$ins1="inscrit";
}
else
{
$sig1="Mme";
$col="red";
$naiss1="Née le ";
$ins1="inscrite";
}
?>
<table border="2" bordercolor="<?php echo $col?>"align="left" cellpadding="2">
<tr>
<td align="left">
<b><font color="<?php echo $col?>">
<?php
echo $sig1."".$nom1.""."<br>";
echo $nass1."".$datenaiss1."".$lieunaiss1."<br>";
echo "contact:"."".$cel1."/".$tel1."<br>";
echo "Email:"."".$mail1."<br>";
echo $ins1."".$hinscrit1;
?>
</b></font>
</td>
</tr>
</table>
<table border="0" height="5">
<tr>
<td>
</td>
</tr>
</table>
<?php
}
}
mysql_close();
?>
</td>
<td>
<?php
$ds=date("Y-m-d");
$sh="06:00:00";
$dh="12:00:00";
$hh="18:00:00";
include("./codes/connexion.php");
$req2="select*from student where dateinscrit='$ds' and heurein>=$sh and heurein<$dh order by id desc";
$env2=mysql_query($req2);
$num2=mysql_num_rows($env2);
if($num2!=0)
{
while($recup2=mysql_fetch_assoc($env2))
{
$nom2=strtouper($recup2["nom"]);
$prenom2=UCwords($recup2["prenom"]);
$sexe2=$recup2["sexe"];
$datenaiss2=$recup2["datenaiss"];
$lieunaiss2=UCfirst($recup2["Lieunaiss"]);
$cel2=$recup2["cel"];
$tel2=$recup2["tel"];
$mail2=strtolower($recup1["email"]);
$hinscrit2=$recup2["heureinscri"];
if($sexe2=="M")
{
$sig2="Mr";
$co2="blue";
$naiss2="Né le ";
$ins2="inscrit";
}
else
{
$sig2="Mme";
$col="red";
$naiss2="Née le ";
$ins2="inscrite";
}
?>
<table border="2" bordercolor="<?php echo $col?>"align="left" cellpadding="2">
<tr>
<td align="left">
<b><font color="<?php echo $col?>">
<?php
echo $sig2."".$nom2.""."<br>";
echo $nass2."".$datenaiss2."".$lieunaiss2."<br>";
echo "contact:"."".$cel2."/".$tel2."<br>";
echo "Email:"."".$mail2."<br>";
echo $ins2."".$hinscrit2;
?>
</b></font>
</td>
</tr>
</table>
<table border="0" height="5">
<tr>
<td>
</td>
</tr>
</table>
<?php
}
}
mysql_close();
?>
</td>
</tr>
</table>