如何显示两个表中的数据仅用于匹配记录

Question

I have two tables. First one stores user information called "users"

| user | password | email           |
|:---- |:--------:| ---------------:|
| user1  | pass1  | email@email.com |
| user2  | pass1  | email@email.com |
| user3  | pass1  | email@email.com |

and second "materials" and it stores information about what every user has

| user | lumberjack| farmer etc        |
|:---- |:---------:| -----------------:|
| user1| 10        | 20                |
| user2| 20        | 50                |
| user3| 30        | 40                |

I want to get data from 2nd tables but only for specific user.

I tried this but it shows materials for every user that is in both tables. And what i want to do is to show one row from 2nd table that has same user name as logged. For example if user1 is logged i want to show that he has 10 lumberjacks and 20 farm, if user2 is logged then 20 lumberjacks 50 farms etc.

$sql = "SELECT lumberjack, stonemanson, farmer FROM materials JOIN users ON materials.user = users.user  ";}

  $res = $conn->query($sql);

  if ($res->num_rows > 0)
  {
    while ($row = $res->fetch_assoc())
    {
      echo "Lumberjack: " . $row["lumberjack"]. " Stonemanson: " . $row["stonemanson"]. " Farmer: " . $row["farmer"].  "<br>";
    }
  }

Answer 1

Concerning your query add WHERE clause to it.

Eg if the user id is 26 SQL query will be

SELECT lumberjack, stonemanson, farmer FROM materials JOIN users ON materials.user = users.user WHERE users.user=26

And checking your table structure, if you will not need any data from the users table then you shouldn't bother to use JOIN

this will also work fine and it'll be faster SELECT lumberjack, stonemanson, farmer FROM materials WHERE materials.user =26

NB: using query() makes your code vulnerable to SQL injection You should use Mysqli or PDO prepared statement.

Stackoverflow has many answers on that. So after you have resolved your issue, then start read on SQL injection and use of PDO or Mysqli prepared statement