Mysql 獲取訂單表中每個會員的最新訂單

SELECT 
    uid,
    MAX(id) id 
  FROM
    project_order 
  GROUP BY uid

說明：GROUP BY 分組 col 中必須有分組的字段出現，其他字段只能使用聚合函數，否則會報錯

SELECT 
    uid,
    MAX(expire_time) expire_time,MAX(id) id ,order_no
  FROM
    project_order 
  GROUP BY uid

報錯：錯誤代碼： 1055
Expression #4 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'movie.project_order.order_no' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

可以看出是sql_mode 問題。這里不再陳述

方法一：

SELECT 
   a.*
FROM
  project_order a 
WHERE 1 > 
  (SELECT 
    COUNT(*) 
  FROM
    project_order 
  WHERE uid = a.uid 
    AND id > a.id) 
ORDER BY a.uid 

說明：這種方式可以輸出任意你想要的字段

還有以下幾種：

方法二：

 SELECT 
   a.*
FROM
  project_order a 
  INNER JOIN 
    (SELECT 
      uid,
      MAX(id) id 
    FROM
      project_order 
    GROUP BY uid) b 
    ON a.uid = b.uid 
    AND a.id = b.id 
ORDER BY a.uid

 SELECT 
  a.*
FROM
  project_order a 
WHERE NOT EXISTS 
  (SELECT 
    1 
  FROM
    project_order 
  WHERE uid = a.uid 
    AND id > a.id)

SELECT 
  a.*
FROM
  project_order a 
WHERE id = 
  (SELECT 
    MAX(id) 
  FROM
    project_order 
  WHERE uid = a.uid) 
ORDER BY a.uid 

SELECT 
  a.*
FROM
  project_order a,
  (SELECT 
    uid,
    MAX(id) id 
  FROM
    project_order 
  GROUP BY uid) b 
WHERE a.uid = b.uid 
  AND a.id = b.id 
ORDER BY a.uid 

說明：當uid沒有設置為索引的時候，以上執行效率差別明細，當設置uid為索引時，差別幾乎可以忽略。