如何解决这个MySQL查询

Question

I have 3 mysql tables

• user(u_id(p),name) ,
• team(t_id(p),u_id(f),t_name,t_money,days_money) and
• history(t_id(f),day,d_money) .

Now I have to display leaderboard using php.

I tried this.

SELECT t_id FROM team;

got result.

then, in for loop

foreach($tid_all as $tid)
{
     $que = $db_con->prepare("SELECT d_money, t_name FROM team, history WHERE t_id= '".$tid['t_id']."' && day='1'");

     $que->execute();

        while($info = $que->fetch(PDO::FETCH_NUM))
        {

                  echo "<tr>";
                  echo  "<td>".$info[0]."</td>";
                  echo  "<td>".$info[1]."</td>";
                  echo "</tr>";
         }
}

but it didnt work. any solution?

Solution 1: i tried this and it worked.

`SELECT d_money, t_name FROM team, history WHERE history.t_id=$tid['t_id'] AND team.t_id=history.t_id`

is it correct way or not?

thanks everyone for help.

Question : is it possible to order the result table by d_money? i want it in descending order.

Answer 1

There is no && in MySQL Query. Replace that with AND Operator on your query.

Answer 2

Since you want to get the data from the two tables, then JOIN the two tables instead of doing that with a loop:

SELECT
  h.d_money,
  t.t_name
FROM team AS t
INNER JOIN history AS h ON t.t_id = h.t_id;

Run this single query once and you will get what you want. You can also add a WHERE clause at the end of it the way you did in your query.

Answer 3

尝试这个

SELECT d_money, t_name FROM team, history WHERE team.t_id= '".$tid['t_id']."' AND history.t_id= '".$tid['t_id']."' && day='1'

Answer 4

用AND替换&& AND尝试像这样：

"SELECT d_money, t_name FROM team, history WHERE t_id= '".$tid['t_id']."' AND day='1' order by d_money DESC "

Answer 5

Can you replace

 WHERE t_id= '".$tid."' AND day='1'

instead of

 WHERE t_id= '".$tid['t_id']."' && day='1'