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从MAX(ID),MIN(ID)MYSQL查询获取更多信息?

[英]Get more info from a MAX(ID), MIN(ID) MYSQL query?

How to get more columns from MAX(ID), MIN(ID) MYSQL query? 如何从MAX(ID), MIN(ID) MYSQL查询中获取更多列?

Currently I get only two values: MAX(ID) & MIN(ID) from this query: 目前我只得到两个值:来自此查询的MAX(ID) & MIN(ID)

SELECT MIN(ID), MAX(ID) FROM mytable WHERE mytable.series = 'white' ;

Need to get something like this-pseudo-query: 需要得到像这样的伪查询:

SELECT  column1, column2
FROM    mytable 
WHERE   series = 'white'
AND ID=Max(ID)
'AND GET ME ALSO'
WHERE   series = 'white'
AND ID=Min(ID);`

It should return 2 rows for the column 'series' that equals 'white'. 对于“系列”列,它应返回2行,等于“白色”。

1st with column1 and column2 for ID=Min(ID). 第1列为column1,第2列为ID = Min(ID)。 2nd with column1 and column2 for ID=Max(ID). 第2列为column1,第2列为ID = Max(ID)。

But how? 但是怎么样?

Here is an approach using UNION : 这是一种使用UNION的方法:

SELECT column1, column2
FROM mytable
WHERE series = 'white' AND ID IN
(    
    SELECT MIN(ID) FROM mytable WHERE series = 'white'
    UNION
    SELECT MAX(ID) FROM mytable WHERE series = 'white'
)

For good performance add a combined index on (series, id) . 为了获得良好的性能,请在(series, id)上添加组合索引。

Or another variation which may have better performance: 或者可能具有更好性能的另一种变体:

(
    SELECT column1, column2
    FROM mytable
    WHERE series = 'white'
    ORDER BY ID
    LIMIT 1
)
UNION
(
    SELECT column1, column2
    FROM mytable
    WHERE series = 'white'
    ORDER BY ID DESC
    LIMIT 1
)

This will also be able to use the combined index on (series, id) . 这也可以在(series, id)上使用组合索引。

A simpler solution: 更简单的解决方案:

SELECT a.column1, a.column2
FROM   mytable a
JOIN   (
       SELECT MIN(ID) AS minid, MAX(ID) AS maxid
       FROM   mytable
       WHERE  series = 'white'
       ) b ON a.ID IN (b.minid, b.maxid)

It's exactly as you say: 就像你说的那样:

SELECT
  column1, column2
FROM 
  mytable as m, 
  (SELECT MIN(ID) as mid, MAX(ID) as xid 
   FROM mytable WHERE mytable.series = 'white'
   ) t
WHERE 
  m.ID = t.mid or m.ID = t.xid;

The select in parentheses is the inner select that you can use just like another table. 括号中的select是内部选择,您可以像使用另一个表一样使用。

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