Question

我有两张这样的桌子我希望按日期提供最新数据

tbl_fruit_info
+-----+--------+
| sId | sName  |
+-----+--------+
|   1 | Apple  |
|   2 | Banana |
|   3 | Orange |
+-----+--------+

tbl_fruit_data
+------------+----------+-------------+
|    date    | fruit_id | fruit_price |
+------------+----------+-------------+
| 2017-01-26 |        1 | 44.7        |
| 2017-01-27 |        1 | 51          |
| 2017-01-25 |        1 | 71.5        |
| 2017-01-21 |        2 | 44          |
| 2017-01-23 |        2 | 55          |
| 2017-01-24 |        2 | 71          |
+------------+----------+-------------+

我试过这个

                    SELECT tbl_fruit_info.*, tbl_fruit_data.*
                    FROM tbl_fruit_data 
                    LEFT JOIN 
                        tbl_fruit_info ON tbl_fruit_info.sId = tbl_fruit_data.fruit_id 
                    GROUP BY 
                        tbl_fruit_info.sId
                    ORDER BY 
                        max(tbl_fruit_data.date) DESC;

我正在寻找的输出是这样的：

+-----+--------+----------------------------+
| sId | sName  | date          |fruit_price | 
+-----+--------+----------------------------+
|   1 | Apple  | 2017-01-27    | 51         |
|   2 | Banana | 2017-01-24    | 71         |
|   3 | Orange | 0000-00-00    | 0          |
+-----+--------+----------------------------+

但我明白了：

+-----+--------+----------------------------+
| sId | sName  | date          |fruit_price | 
+-----+--------+----------------------------+
|   1 | Apple  | 2017-01-26    | 44.7       |
|   2 | Banana | 2017-01-21    | 44         |
+-----+--------+----------------------------+

非常感谢任何协助。

Answer 1

hash_table_create(hash_modulo);
hash_table_create(hash_universal);

Answer 2

SELECT fi.*, fd.*
FROM tbl_fruit_data fd
  FULL OUTER JOIN tbl_fruit_info fi ON fi.sId = fd.fruit_id
WHERE fd.fruit_id IS NULL OR fd.date = (
  SELECT max(fd_inner.date)
  FROM tbl_fruit_data fd_inner
  WHERE fd_inner.fruit_id = fd.fruit_id
) 
ORDER BY fd.date DESC;

更新2017-01-30：在tbl_fruit_info中合并行，现在在tbl_fruit_data中没有相应的行。

Answer 3

好的，这就是。

**获取水果的最新价格，没有价格的ADDED水果

SELECT d1.date, d1.fruit_id, d1.fruit_price, i.sId, i.sName 
FROM tbl_fruit_info i
LEFT JOIN tbl_fruit_data d1
ON d1.fruit_id = i.sId
WHERE d1.date = (SELECT MAX(d2.date) 
                FROM tbl_fruit_data d2
                WHERE d2.fruit_id = d1.fruit_id
                 )
UNION
SELECT CAST('0001-01-01' AS datetime) date, i.sId fruit_id, 0 fruit_price, i.sId, i.sName
FROM tbl_fruit_info i
WHERE i.sId NOT IN (SELECT d2.fruit_id FROM tbl_fruit_data d2)

对相同数据进行测试的Sql小提琴有问题：

http://sqlfiddle.com/#!9/872ed4/9

使用这些定义

CREATE TABLE tbl_fruit_info
    (`sId` int, `sName` varchar(6))
;

INSERT INTO tbl_fruit_info
    (`sId`, `sName`)
VALUES
    (1, 'Apple'),
    (2, 'Banana'),
    (3, 'Orange')
;


CREATE TABLE tbl_fruit_data
    (`date` datetime, `fruit_id` int, `fruit_price` int)
;

INSERT INTO tbl_fruit_data
    (`date`, `fruit_id`, `fruit_price`)
VALUES
    ('2017-01-26 00:00:00', 1, 44.7),
    ('2017-01-27 00:00:00', 1, 51),
    ('2017-01-25 00:00:00', 1, 71.5),
    ('2017-01-21 00:00:00', 2, 44),
    ('2017-01-23 00:00:00', 2, 55),
    ('2017-01-24 00:00:00', 2, 71)
;

Answer 4

使用dadde的小提琴（带一些调整） - 并假设MySQL标签是正确的......

CREATE TABLE tbl_fruit_info
    (`sId` int auto_increment PRIMARY KEY, `sName` varchar(6))
;

INSERT INTO tbl_fruit_info
    (`sId`, `sName`)
VALUES
    (1, 'Apple'),
    (2, 'Banana'),
    (3, 'Orange')
;


CREATE TABLE tbl_fruit_data
    (`date` datetime, `fruit_id` int, `fruit_price` int, primary key (fruit_id,date))
;

INSERT INTO tbl_fruit_data
    (`date`, `fruit_id`, `fruit_price`)
VALUES
    ('2017-01-26 00:00:00', 1, 44.7),
    ('2017-01-27 00:00:00', 1, 51),
    ('2017-01-25 00:00:00', 1, 71.5),
    ('2017-01-21 00:00:00', 2, 44),
    ('2017-01-23 00:00:00', 2, 55),
    ('2017-01-24 00:00:00', 2, 71)
;

SELECT a.sid
     , a.sname
     , COALESCE(b.date,'0000-00-00') date
     , COALESCE(b.fruit_price,0) fruit_price 
  FROM tbl_fruit_info a 
  LEFT 
  JOIN 
     ( SELECT x.* 
         FROM tbl_fruit_data x 
         JOIN 
            ( SELECT fruit_id, MAX(date) date 
         FROM tbl_fruit_data 
        GROUP 
           BY fruit_id
     ) y 
    ON y.fruit_id = x.fruit_id 
   AND y.date = x.date) b 
    ON b.fruit_id = a.sid;
+-----+--------+---------------------+-------------+
| sid | sname  | date                | fruit_price |
+-----+--------+---------------------+-------------+
|   1 | Apple  | 2017-01-27 00:00:00 |          51 |
|   2 | Banana | 2017-01-24 00:00:00 |          71 |
|   3 | Orange | 0000-00-00          |           0 |
+-----+--------+---------------------+-------------+

Answer 5

create table #t1
(id int,name varchar(100));


create table #t2(
[date] date,
id int,
price float)

insert into #t1
select 1,'Apple'
union
select 2,'Banana'

insert into #t2
select getdate()-3,1,33.2
union
select getdate()-2,1,30.5
union
select getdate()-4,1,23.4
union
select getdate()-3,2,21
union
select getdate()-2,2,35

查询

select q.name,t2.* from (
select  t1.id,t1.name,MAX(t2.date) as date from #t1 t1
inner join #t2 t2 on t1.id=t2.id
group by t1.id,t1.name
) as q inner join #t2 t2
on q.id=t2.id and t2.date=q.date

编辑：修复，用子查询替换CTE，感谢dadde指出CTE在MySQL中不受支持。 CTE或子查询在这里做同样的工作

mySql查询组按日期顺序不起作用

5 个答案: