從每個GROUP BY（unique_id）和ORDER BY編號選擇具有MAX ID的行

Question

我擁有帶id，unique_id和order_number的表。

1. 我通過UNIQUE_ID
2. 我想借此從每個組
3. 而最後一件事，我想那種由ORDER_NUMBER行

我也有MAX ID行希望將行幾個WHERE子句。這是我嘗試不工作：

SELECT MAX(id) AS id 
    , order_number 
    FROM table 
WHERE final = 0 
    AND username = '$username' 
    AND active = 1 
GROUP 
    BY unique_id 
ORDER 
    BY order_number 

Answer 1

您可以使用查詢作爲子查詢：

SELECT * 
FROM table 
WHERE id IN (SELECT MAX(id) AS id 
      FROM table 
      WHERE final=0 AND username='$username' AND active=1 
      GROUP BY unique_id) 
ORDER BY order_number 

，或者如果id不是唯一的，使用JOIN：

SELECT t1.* 
FROM table AS t1 
JOIN (SELECT MAX(id) AS max_id, unique_id 
     FROM table   
     WHERE final=0 AND username='$username' AND active=1 
     GROUP BY unique_id 
) AS t2 ON t1.unique_id = t2.unique_id AND t1.id = t2.unique_id 
ORDER BY order_number 

Answer 2

試試這個：

SELECT id, redni_broj 
FROM table 
WHERE final=0 AND username='$username' AND active=1 AND 
    id IN (
       SELECT MAX(id) FROM table table2 
       WHERE table.unique_id = table2.unique_id 
     ) 
GROUP BY unique_id 
ORDER BY order_number;