insert data if the date time is different - php

Question

I have 2 tables: reservations_client and tables_clients
The reservation_client has 3 fields:
id, name_client, date, table
The table_clients has 2 fields:
id, name_table
When a client wants to reserve they put his name, the date, and choose a table, but there is a problem: 2 clients cant use the same table.
What I need is it to only insert data into the database when the date is different. If the date is the same (i.e., someone's already using the table), it should send an error;
I tried using an unique key but it sends me an error even if the date is different.
My PHP code:
$editFormAction = $_SERVER['PHP_SELF'];
if (isset($_SERVER['QUERY_STRING'])) {
$editFormAction .= "?" . htmlentities($_SERVER['QUERY_STRING']);
}
if ((isset($_POST["MM_insert"])) && ($_POST["MM_insert"] == "form1")) {
$insertSQL = sprintf("INSERT INTO reservations_clients (user, number_person, table, date) VALUES (%s, %s, %s, %s)",
GetSQLValueString($_POST['user'], "text"),
GetSQLValueString($_POST['number_person'], "int"),
GetSQLValueString($_POST['table'], "int"),
GetSQLValueString($_POST['date'], "text"),
mysql_select_db($database_conexionbdd, $conexionbdd);
$Result1 = mysql_query($insertSQL, $conexionbdd) or die(mysql_error());
mysql_select_db($database_conexionbdd, $conexionbdd);
$query_table = "SELECT * FROM tables";
$table = mysql_query($query_table, $conexionbdd) or die(mysql_error());
$row_table = mysql_fetch_assoc($table);
$totalRows_tables = mysql_num_rows($table);
And the form clients fill out:
<form method="post" name="form1" action="<?php echo $editFormAction; ?>">
<table align="center">
<tr valign="baseline">
<td nowrap align="right">Number_person:</td>
<td><input type="text" name="Number of persons" value="" size="32"></td>
</tr>
<tr valign="baseline">
<td nowrap align="right">table:</td>
<td><select name="numero_mesa">
<?php
do {
?>
<option value="<?php echo $row_table['idtable']?>" <?php if (!(strcmp($row_tables['idtable'], $row_table['idtable']))) {echo "SELECTED";} ?>><?php echo $row_table['name_table']?></option>
<?php
} while ($row_table = mysql_fetch_assoc($table));
?>
</select></td>
<tr>
<tr valign="baseline">
<td nowrap align="right">date:</td>
<td><input type="text" name="fecha" size="32" id="datepicker" /></td>
</tr>
<tr>
<td nowrap align="right"> </td>
<td><input type="submit" value="Enviar"></td>
</tr>
</table>
<input type="hidden" name="user" value="<?php echo $row_user['user']; ?>">
<input type="hidden" name="MM_insert" value="form1">
</form>
<p> </p>

Answer 1

I'm confused about how you're using your database setup; seems the only issue is with the reservation_client table.
It looks like when you set the unique constraint, you only included table as a unique key instead of both table and date. One sets a unique key on one column, one sets it on the combination of columns. This combination as opposed to one column is extremely important. To fix this, go to the database you're working in, remove any unique keys in the reservation_client and :
ALTER TABLE `reservation_client` ADD UNIQUE (`table`, `date`);
Essentially what this does is say that in order to insert an entry, there can't be any row that has the same table and date values. It essentially sets a unique combination instead of a unique key. You're going to want to make sure you handle the error that's returned, whether that means catching it within your PHP or setting some kind of ON DUPLICATE KEY action in your query. I'm not sure the exact circumstances, so you'll have to play around with that.

Answer 2

You can just query first if the table and date is present in the database.
Select * From reservation_clients Where Date = $date And table = $table
if the result is empty then you can proceed to insert the data.

Answer 3

Why don't you use where condition like this
$q_num = mysql_query('select * from reservations_client where date = "the date the client chose" and table = "the table the client chose"');
$r_num = mysql_num_rows($q_num);
and make a condition if $r_num is > 0 then send error, else insert data

Answer 4

if you are using php, get the date to the server side. Then, if you need second by second accuracy you can just compare those as strings
if($dateFromDB==date("Y-m-d H:i:s"))
{
// go ahead and do your business
}
if you are looking to have 2 different days however, you can use the following
$today=explode(" ",date("Y-m-d H:i:s"));
$today=$today[0];
$dateFromDB=explode(" ",$dateFromDB);
$dateFromDB=$dateFromDB[0];
if($dateFromDB==$today)
{
// go ahead and do your business
}