[Database Design and segregation of reponsiblilites]

I don't see any problem with just having one database and multiple tables, and then give different applications different type of access to the data (using views or stored procedures).

 

There is no need for using multiple databases when you have connections to different tables.

 

[Wondering if this class is too overboard for 'practicalness']

I'm not a backend developer, just a good developer. I can't tell you the internals of the JDBC but the idea still remains that it's polymorphic and independent of the database and database specific syntax. Sorry I can't elaborate any further how

Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
Connection conn = DriverManager.getConnection("jdbc:derby:COFFEES");
PreparedStatement updateSales = con.prepareStatement(
        "UPDATE COFFEES SET SALES = ? WHERE COF_NAME LIKE ? ");
updateSales.setInt(1, 75); 
updateSales.setString(2, "Colombian"); 
updateSales.executeUpdate():

runs. Perhaps it deals with the database drivers that JDBC uses as a proxy, but I have no clue about the java internals, jut the theory.

 

To me, that looks a lot like PDO.

http://www.php.net/pdo

[How to design my usermodule?]

 

I get the following Notice error:

Notice: Undefined index: first in C:\xampp\htdocs\web\HTML_User.php on line 17

 

It's becuase the variabels used in the form are not set yet. How do i work around this?

 

<?php
$first = isset($_POST['first']) ? $_POST['first'] : "";
...
First: <input name="first" type="text" value="{$first}" /> {$errors['first']} <br />
?>

[Avoid Getters and Setters?]

I always use setName() and getName() since I believe that the __get and __set methods removes the clarity of what types of properties an object have. I know that __get and __set can create a more dynamic structure, but that is the price I pay for a clearer code.

 

[Static Util Classes: Who's creates the DB Connection?]

I would recommend the second one in your example since the first one adds a dependency that the Util class needs to know about the database when you write test-cases

[Minimalism]

One site that I find minimalistic but with much information, is http://zenhabits.net. Maybe get some ideas from there

[[SOLVED] Parent Variable as Default Parameter]

class b extends a{

     function show_name($name = null){

          if ($name != null)
              echo $name;
          }
          else {
              echo $this->name; 
         }
     }
}

 

That should work

[Temporal database with references]

But this will not work, since the ID will change every time a change is made to the user row (id column has auto_increment)

You would never update a primary key. It is used in the WHERE claus of the update query to define what record to update

UPDATE users SET name='joe', email='joe@123.com'  WHERE userId='123'

 

I suggest you spend some time on database normalisation

 

Yea, this is the case for normal database with no temporal support. In temporal database you need an ID for each update to the object in a unique row.

 

After some thinking and help from a friend, here is the solution for the database schema:

 

-- Author: Johan Grahn
-- Database schema for my blog

DROP DATABASE IF EXISTs high_blog;
CREATE DATABASE high_blog CHARACTER SET = utf8;

USE high_blog;

CREATE TABLE user (
        username varchar(40) NOT NULL,
        password varchar(40) NOT NULL,
        first_name varchar(40) NOT NULL,
        last_name varchar(50) NOT NULL,

        id int NOT NULL,
        revision int NOT NULL DEFAULT 1,
        st timestamp NOT NULL DEFAULT now(),
        et timestamp NULL DEFAULT NULL,

        PRIMARY KEY(id, revision)

) ENGINE=innodb CHARSET=utf8;

CREATE TABLE blog_entry (
        id int NOT NULL,
        revision int NOT NULL DEFAULT 1,
        title varchar(100) NOT NULL,
        content text NOT NULL,
        st timestamp NOT NULL DEFAULT now(),
        et timestamp NULL,

        author int NOT NULL,
        author_revision int NOT NULL,
        PRIMARY KEY (id, revision),
        FOREIGN KEY (author, author_revision) REFERENCES user(id, revision)

) ENGINE=innodb CHARSET=utf8;

 

In this schema, I store each update to the id in a unique revision so that each user with a given ID can have multiple revisions (each revision contains the updated data for the user).

 

[Temporal database with references]

blog_posts

========

blog_id

user_id

blog_content

 

blog_posts.user_id = user.id

 

But this will not work, since the ID will change every time a change is made to the user row (id column has auto_increment), since a new row is inserted for every change so that you can track each change.

 

Hm, I think I need to read more about this.

 

 

 

[Temporal database with references]

Hello!

 

I'm trying to build a blog and use a database design that can record history using temporal data.

 

I have a user table that looks like this:

CREATE TABLE user (
id int NOT NULL AUTO_INCREMENT,
username varchar(40) NOT NULL,
password varchar(32) NOT NULL,
first_name varchar(40) NOT NULL,
last_name varchar(50) NOT NULL,
-- Temporal columns
st timestamp NOT NULL DEFAULT now(),
et timestamp NULL DEFAULT NULL,

PRIMARY KEY(id)

) ENGINE=innodb CHARSET=utf8;

 

Now I want to have a blog_post table with a author id connected to the user table, but how do I uniquely store a identifier to the user?

 

My first though was to store ID + st in blog_post table, but it doesn't seem right.

 

Any hints on this?

 

[Automatic database updation based on files in a directory?]

I would recommend writing a shell-script that polls your directory (or even use inotify) and runs mysql queries if any new files are added.

 

God luck!

[[SOLVED] Why doesn't this get the name? C++]

And replace

 

#include <iostream.h>

 

with

 

#include <iostream>

 

The first one is meant for C-compiler, not C++

 

[[SOLVED] Multiple mysql databases]

Yea, you need one connection to each database.

 

No, MySQL will not know in which database the given table is, you will have to tell him, by using the appropriate connection.

 

 

[when to delete old forum topics and their replies?]

what do you mean MySQL doesn't load all content into memory? and what is Sphinx? i developed a simple forum with two tables, Topics and Responses. For the sake of discussion, if my forum EVER got to be as used as phpfreaks would i have to worry about having TOO much in my database?

 

I think that with todays hardware, you will run out of bandwidth (e.g. many users) before running out of disk space, unless you do a TERRIBLE database design.

[question about my programming method.]

yah, but i was reading one article and it said something about big classes or using classes for things they are not meant for

which is what i am doing here

and i'm just wondering if there's something wrong about it.

 

Sounds like a very strange article, can you post a link to it ?

 

A class should have ONE purpose, and ONE purpose only. Better to have 10 small classes than 1 big. Better maintainability and structure.

[[SOLVED] Database field in textbox]

You need to a hidden field in the form that stores the ID of the row that you want to update, like this:

 

<input type="hidden" name="id" value="<?php echo $id?>" />

 

And then, on the process.php page, get the ID and then perform the query:

 

<?php
$estDev = $_POST['estimatedDelivery'];
$id = $_POST['id'];

mysql_query("UPDATE 'deliveries' SET 'estimatedDelivery' = '$estDev' WHERE row_id = '$id");

?>

 

This is just an example, and you need to modify it to fit your need, but it is a start

 

[question about my programming method.]

Because that piece of code is just like regular functional coding.

 

No, it's procedural. Functional programming is a much different paradigm.

 

Yea, my bad. Wrong word

[[SOLVED] Database field in textbox]

What is stored in  $_POST['estimatedDelivery'] ?

[Code Speed Help]

I whould say that the first thing to check is to see how much time the database query takes, and if the query uses correct indexes.

 

Look up  EXPLAIN SELECT with your MySQL manual

[[SOLVED] Do minor errors/notices that are not reported or displayed hurt performance?]

Yea, silly me, haven't had my coffee yet

 

Of course it will take some computing time for each error

[question about my programming method.]

Are you trying to use OO design? Because that piece of code is just like regular functional coding.

 

But you are thinking correct when you separate form code from view code.

 

[[SOLVED] Do minor errors/notices that are not reported or displayed hurt performance?]

No, there will not be any performance losses, but why do you run a script with a lot of errors? Why not fix the errors?

[when to delete old forum topics and their replies?]

I whould agree that data never gets removed since the old data is used for history queries. Data can be moved to other tables but not completely removed. Storage space is not expensive

[License in code]

This is just a quick question:

 

To add copyright to my code, I have added this to each PHP file and HTML file. Is this enough?

 

/*
* $Id$
*
* Copyright (c) 2008 Johan Grahn 
* Released under the BSD license
*
*/

 

 

[[SOLVED] Trying to insert 15 queries into mysql at once, but only 10 will go.]

Are you using transactions? I mean do you send all INSERT's into one transaction?