【mysql】数据按照时间排序并且去重

今天帮助同事调了一个SQL语句。需求是这个样子滴：查询最近12条搜索的图书记录，并且去重。

数据库现在的数据是这个样子的。

 

他写的SQL语句查询出来是这个样子的：

虽然时间是降序排序的，但是图书的记录不是最新搜索的在前面

 

更改后的SQL是这个样子的：

-- 修改之前的语句

SELECT 
 DISTINCT
  ts.book_basic_id 
FROM
  tl_user_search_record ts 
WHERE
  ts.is_delete = 0 
  AND ts.user_id = '1071009104044093400' 
 ORDER BY  ts.create_time DESC 
  LIMIT 12
  
SELECT *
FROM
  tl_user_search_record ts 
WHERE
  ts.is_delete = 0 
  AND ts.user_id = '1071009104044093400' 
  GROUP BY ts.book_basic_id
ORDER BY
  ts.create_time DESC 
  LIMIT 12
  
 ---------------------------------------------------------------------------------
-- 修改之后的
 
SELECT
  * 
FROM
  ( SELECT * FROM tl_user_search_record ts WHERE ts.is_delete = 0 AND ts.user_id = '1071009104044093400' ORDER BY ts.create_time DESC ) a 
GROUP BY
  a.book_basic_id 
ORDER BY
  a.create_time DESC 
  LIMIT 12
  
        
SELECT DISTINCT
  a.book_basic_id 
FROM
  ( SELECT * FROM tl_user_search_record ts WHERE ts.is_delete = 0 AND ts.user_id = '1071009104044093400' ORDER BY ts.create_time DESC ) a 
  LIMIT 12