关联数据库中不同表的两个元素

Question

I don't know how much to explain this, so I'll give my situation and so you can understand me better.

I have a games webpage. In my db, I have two tables: one with my games (with colums like id, name, description, category (this is a number, not a string) , etc.), and another with my categories (with the id and the name).
When I upload games, instead of assigning into the category column the name of the category, I assign a number, the one which corresponds in the categories table (I do it with a select option like this:

<option value="'.$row['id'].'">'.$row['name'].'</option>

(This is inside a select tag (inside a form) and with a foreach statement so it shows me all the options).

So now, what I want is that when I catch the games from the db with a 'SELECT * FROM games', if I call the category element, instead of getting the id of the category, to assign the id with the category name... I don't know how much to explain it but I hope you can understand me.

So, what should I use?

Answer 1

You can use a LEFT JOIN to pull the category name. Example:

SELECT 
  g.id g_id,
  g.name g_name,
  g.desc g_desc,
  c.name c_name
FROM games g
LEFT JOIN
  categories c
    ON c.id = g.category

This is an example, you'll need to select the proper columns and assign a unique alias.

Answer 2

I think you want to join the tables so you can get the categoryname from the same query.

You can do it like this:

$result = mysql_query("SELECT * FROM games, category WHERE games.category = categoyry.id) or die(mysql_error());
while($row = mysql_fetch_array($result))
{
    echo $row['games.name'].' '.$row['category.name'];
}

Answer 3

you can use just "INNER JOIN or JOIN" to get the result from two tables by just joining them.

`SELECT g.*,c.*
 FROM games g
 INNER JOIN categories c on c.categoryid = g.categoryid;`

this will give you just those which are associated categories. but if you use "Left Join" it would give you everything from games( http://www.sitepoint.com/understanding-sql-joins-mysql-database/ )

`SELECT g.*,c.*
 FROM games g
 LEFT JOIN categories c on c.categoryid = g.categoryid;`