如何从同一个数据库连接2个表？ [英] How do I connect 2 table from same database ?

问题描述

我是PHP，SQL的新手，我想知道是否可以从同一个数据库连接2个表？因此，当我键入相同的课程名称时，它将从另一个表中减少1个可用座位。我的代码很乱，很抱歉



我尝试过：

i am new to PHP,SQL and i would like to know is it possible to connect 2 table from the same database ? so that when i key in the same course name , it will decrease 1 available seat from the other table. my code is in a mess sorry

What I have tried:

<?php 
	require_once ('Database.php'); 
	

	$Name = mysql_real_escape_string ($_REQUEST["Name"]);
	$Course_applied = mysql_real_escape_string ($_REQUEST["Course_applied"]);
	$Email = mysql_real_escape_string ($_REQUEST["Email"]);
	$Contact = mysql_real_escape_string ($_REQUEST["Contact"]);
	$Register_Date = mysql_real_escape_string ($_REQUEST["Register_Date"]);
	
	$sql = "SELECT * FROM tblregistercourse WHERE Name = '" . $Name . "'";

	$result = mysql_query ($sql, $dbconn);
	if (mysql_num_rows ($result) ) {
$sql =("UPDATE tblcourse SET Avail_Seats = Avail_Seats-1  WHERE tblcourse.Course_Name = tblregistercourse.Course_applied");
	}	
	else {
		$sql = "INSERT INTO tblregistercourse (Name, Course_applied, Email, Contact, Register_Date) VALUES ('" . $Name . "', '" . $Course_applied ."', 
		'" . $Email . "', '" . $Contact . "', '" . $Register_Date . "')";
		$result = mysql_query ($sql, $dbconn);
	}
		if ($result) {
			$message = "Registration Successful.";
  echo "<script type='text/javascript'>alert('$message'); window.location='coursedetails.php';</script>";
		} 
		else 
			$sql("UPDATE tblcourse SET Avail_Seats = Avail_Seats-1 WHERE tblcourse.Course_Name = tblregistercourse.Course_applied");
	
		
	echo json_encode($resultStr);
?>

推荐答案

Name = mysql_real_escape_string（

Name = mysql_real_escape_string (

_REQUEST [Name ]）;

_REQUEST["Name"]);

Course_applied = mysql_real_escape_string（

Course_applied = mysql_real_escape_string (

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