mysql - 对多个表使用 UNION 和 WHERE

Question

$whls = querywheels("SELECT * FROM (pc.pn_partcar AS partnum, pc.name_partcar AS descript, pc.weight_partcar AS weight, pc.cycletime_partcar AS cycletime, pc.cavity_partcar AS cavity, p.name_proses AS proses, mm.material_name AS material FROM partcar as pc
        INNER JOIN proses AS p ON p.id_proses = pc.id_prosesfk
        INNER JOIN material AS mm ON mm.material_id = p.material_idfk
        INNER JOIN detailassembly AS da ON da.partcar_idfk = pc.id.partcar

        UNION

        b.pn_barbell AS partnum, b.type_barbell AS descript, wh.cycletime_wheel AS cycletime, wh.cavity_wheel as cavity FROM barbell AS b 

        INNER JOIN wheel AS wh ON b.id_wheelfk = wh.id_wheel
        INNER JOIN detailassembly AS da ON barbell_idfk = b.barbell_id)

        WHERE pc.id_carfk = c.id_car FROM car AS c AND b.id_carfk = c.id_car");

这是我的代码，我不知道我的错在哪里，有人可以帮我纠正这个代码吗？我很困惑。

这是我的数据库

我想要这样的输出

|ID Car|partnum|descript  |cycletime|cavity|proses|material|Qty |
|---------------------------------------------------------------|
|N4002 |22222  |partcar1  | 23      |  3   | PUM  | Plactic| 1  |
|      |22222  |partcar2  | 23      |  3   | PUM  | Plactic| 1  |
|      |22222  |partcar3  | 23      |  3   | PUM  | Plactic| 1  |
|      |22222  |partcar4  | 23      |  3   | PUM  | Plactic| 1  |
|      |22233  |Barbell1  | 20      |  3   | PUM  | Plactic| 2  |

请帮我解决我的代码。我无法运行它。

编辑: 这是我的错误 警告:mysqli_fetch_assoc() 期望参数 1 为 mysqli_result， bool 值在 C:\xampp\htdocs\hwbase\PHP\connect.php 第 17 行给出

这是我的职责

function querywheels($sql)
    {
        global $con;
        //query for takes data

    $result = mysqli_query($con,$sql);
    /*$whls = mysqli_fetch_assoc($result);*/
    $rows = [];
        while ($whs = mysqli_fetch_assoc($result)) {
            $rows []= $whs;
        }
        return $rows;
    }

Answer 1

尝试这个查询

SELECT *
FROM
  (
    SELECT
      pc.pn_partcar AS partnum,
      pc.name_partcar AS descript,
      pc.weight_partcar AS weight,
      pc.cycletime_partcar AS cycletime,
      pc.cavity_partcar AS cavity,
      p.name_proses AS proses,
      mm.material_name AS material,
      pc.id_carfk,
      da.qty
    FROM partcar as pc
    JOIN proses AS p ON p.id_proses = pc.id_prosesfk
    JOIN material AS mm ON mm.material_id = p.material_idfk
    JOIN detailassembly AS da ON da.partcar_idfk = pc.id_partcar

    UNION ALL

    SELECT
      b.pn_barbell AS partnum,
      b.type_barbell AS descript,
      NULL, -- weight
      wh.cycletime_wheel AS cycletime,
      wh.cavity_wheel as cavity,
      NULL, -- proses
      NULL, -- material
      b.id_carfk,
      da.qty
    FROM barbell AS b
    JOIN wheel AS wh ON b.id_wheelfk = wh.id_wheel
    JOIN detailassembly AS da ON da.barbell_idfk = b.id_barbell
  ) q
JOIN car AS c ON q.id_carfk = c.id_car

如果您不需要来自 car 的任何信息(例如 pn_car、description)，您可以仅使用子查询

SELECT
  pc.pn_partcar AS partnum,
  pc.name_partcar AS descript,
  pc.weight_partcar AS weight,
  pc.cycletime_partcar AS cycletime,
  pc.cavity_partcar AS cavity,
  p.name_proses AS proses,
  mm.material_name AS material,
  pc.id_carfk,
  da.qty
FROM partcar as pc
JOIN proses AS p ON p.id_proses = pc.id_prosesfk
JOIN material AS mm ON mm.material_id = p.material_idfk
JOIN detailassembly AS da ON da.partcar_idfk = pc.id_partcar

UNION ALL

SELECT
  b.pn_barbell AS partnum,
  b.type_barbell AS descript,
  NULL, -- weight
  wh.cycletime_wheel AS cycletime,
  wh.cavity_wheel as cavity,
  NULL, -- proses
  NULL, -- material
  b.id_carfk,
  da.qty
FROM barbell AS b
JOIN wheel AS wh ON b.id_wheelfk = wh.id_wheel
JOIN detailassembly AS da ON da.barbell_idfk = b.id_barbell