Check if user has viewed something [closed]

Question

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Closed 9 years ago.

[edit] Removed it, because it is not worth it.

Answer 1

The exact field types will vary some depending on the database you're using, but here's the general technique:

You need a users table with unique IDs:

CREATE TABLE users (
    user_id       INTEGER      PRIMARY KEY,
    email         VARCHAR(50)  NULL,
    password      VARCHAR(32)  NULL
);

And a table for your news items:

CREATE TABLE articles (
    article_id    INTEGER      PRIMARY KEY,
    title         VARCHAR(50)  NULL,
    pubdate       DATETIMESTAMP,
    body          blob or whatever your database supports
);

And finally a table that indicates which users have read which articles:

CREATE TABLE users_articles (
    article_id    INTEGER,
    user_id       INTEGER,
    read_date     DATETIMESTAMP
);

The users_articles table should probably be indexed by article_id, depending the queries you use and how your database chooses to optimize those queries.

Now, to get all of the articles from the last 7 days that user_id 999 has not yet read, your query would look something like this:

SELECT a.title, a.pubdate, a.body
FROM articles a
WHERE a.pubdate > date_sub(NOW(), INTERVAL "7 days")
AND NOT EXISTS (
    SELECT * 
    FROM users_articles ua
    WHERE ua.article_id = a.article_id
        AND ua.user_id = 999
)

Other formulations of this query are possible, of course. And the interval syntax will vary from one database to the next. But that's the gist of it.

Whenever a user reads an article, you can insert/update the users_articles table with the user_id and article_id and the current timestamp. As a side-effect, this also gives you the information about what articles the user has read most recently.

Answer 2

I suggest to make a new table where you can save the relation between the article and the user. The table will look something like this:

newsId | userId | ip | date ...

Answer 3

You've got a users table. And you've got a news table.

You just need something like a user_has_read table...

id
time
user_id
news_id

That way you can add an entry to this table when users first view something to tie them to the news item. Then lookup their user_id in this table to see if they've been here before.

You can now also have a "Recently Viewed" section with links to the last 10 things they've read for ease of navigation.

Answer 4

You could have a boolean flag to determine if something was read or not. When the user gets to whatever you want him/her to read, you can go to the database and set that flag to true, showing that that record has already been seen by a specific user.