selliottsxm

When setting up foreign keys is there a problem with the foreign key in table b (for example) that is linked to a primary key in table A, also being a primary key? Or is it a better idea to set up a surrogate primary key for Table B?

I guess what Hollywood does and kill the third one off? All joking aside thanks for the help. You made it very clear as to how my tables will relate and how to make them compliant

So a different row for each actor with the movie_id being the same as opposed to having actor_1, actor_2 columns?

HI, Hope someone can clarify for me. I'm refering to the examples used in Chapeter 6 regarding the movie database. I have to build a database very similar. Currently all the data is stored in an excel spreadsheet. I have one column for actors (multiple values each cell) which contains all the actors names (groan not separated by last and first names), and the names are sperated by pipes. I also have a director column (1 value each cell), studio column (1 value each cell) and genre (multiple values each cell) column which also uses pipes as a separator. I realize that I have to create separate tables. In the example given the movie-actors table has two fields, movie_id and actor_id. Wouldn't that end up violating the 2NF compliancy rule since the movie_id would have to be in multiple records with each actor? In other words movie_id 1001 has 4 actors. Wouldn't that require 4 rows defining each actor? Help Steve

Thanks again. It's now crystal clear

Thanks so much guys, I really appreciate it. I'm assuming that the paramaters in the function call are passed in the same order? In other words: $cost = calculate_trip_cost($_POST['distance'], $_POST['efficiency'], $_POST['gallon_price']); is passed to the defined $miles, $mpg, $ppg in the same order?

Hello, I'm pasting a php file below that is one of the exercises in PHP and MYSQL for Dynamic Web Sites. I'm referring to chapter 3, page 105 where Larry discusses returning values from a function. Here is my question in a nutshell. When defining the function calculate_trip_cost three variable are set $miles, $mpg and $ppg. I don't understand how these variables work, where do the values come from? They aren't referred to again in the script. Could someone, bearing in mind that I'm new at this, explain it a little? Any help would be so appreciated. I hate to move on without understanding it completely. Thanks in advance, Steve. The php is below: <?php #Script 3.5 - calculator.php // This fucntion creates a radio button. // The function takes two arguments: the value and the name // The function alos makes the button "sticky". function create_radio($value, $name = 'gallon_price') { // Start the element: echo '<input type="radio" name="' .$name.'" value="' .$value.'"'; //Check for stickiness if (isset($_POST[$name]) && ($_POST[$name] == $value)) { echo 'checked="checked"'; } echo "/> $value"; } //End of create_radio()function //This function calculates the cost of the trip. //The funcion takes three arguments: the distance, the fuel efficiency and the price per gallon //The function returns the total cost. function calculate_trip_cost($miles, $mpg, $ppg) { // Get the number of gallons: $gallons = $miles/$mpg; // Get the cost of these gallons $dollars = $gallons/$ppg; //Return the formatted cost: return number_format($dollars, 2); } // End of calculate_trip_cost() function. $page_title = 'Trip Cost Calculator'; include ('includes/header.html'); // Check for form submission if ($_SERVER['REQUEST_METHOD'] == 'POST') { // Minimal Form Validation if (isset ($_POST['distance'], $_POST['gallon_price'], $_POST['efficiency']) && is_numeric($_POST['distance']) && is_numeric($_POST['gallon_price']) && is_numeric($_POST['efficiency'] ) ) { // Calculate the results $cost = calculate_trip_cost ($_POST['distance'], $_POST['efficiency'], $_POST['gallon_price']); $hours = $_POST['distance'] / 65; // Print the results echo '<h1> Total Estimated Costs </h1> <p>The total cost of driving '.$_POST['distance'].' miles, averaging' .$_POST['efficiency'] .' miles per gallon, and paying an average of $'.$_POST['gallon_price'].' per gallon, is $ '.$cost. '.If you drive at an average of 65 miles per hour, the trip will take approximately ' . number_format($hours, 2) . ' hours.</p>'; } else {//Invalid submitted values. echo '<h1>Error!</h1> <p class="error">Please enter a valid distance, price per gallon and fuel efficiency.</p>'; } } // End of main submission IF. ?> <h1>Trip Cost Calculator</h1> <form action="calculator.php" method="post"> <p>Distance (in miles): <input type="text" name="distance" value="<?php if (isset($_POST['distance'])) echo $_POST['distance'];?>"/></p> <p>Ave. Price Per Gallon: <span class="input"> <?php create_radio('3.00'); create_radio('3.50'); create_radio('4.00'); ?> </span></p> <p> Fuel Efficiency: <select name="efficiency"> <option value="10" <?php if (isset ($_POST['efficiency']) && ($_POST['efficiency'] == '10')) echo 'selected="selected"';?>>Terrible</option> <option value="20"<?php if (isset ($_POST['efficiency']) && ($_POST['efficiency'] == '20')) echo 'selected="selected"';?>>Decent</option> <option value="30"<?php if (isset ($_POST['efficiency']) && ($_POST['efficiency'] == '30')) echo 'selected="selected"';?>>Very Good</option> <option value="50"<?php if (isset ($_POST['efficiency']) && ($_POST['efficiency'] == '50')) echo 'selected="selected"';?>>Outstanding</option> </select></p> <p><input type="submit" value="Calculate!" /></p> </form> <?php include ("includes/footer.html"); ?>