---
title: 'mysql - 取得多筆max資料'
disqus: hackmd
---

mysql - 取得多筆max資料
===

## Table of Contents

[TOC]

## 情境

我想要取得IndexSn為5的且Hour為最大值多筆資料。

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SELECT t.*
FROM `tablename` t
JOIN (SELECT max(`Hour`) AS mxHour FROM `tablename`) x
ON x.mxHour = t.`Hour`
AND t.IndexSn = 5;

> tablename為資料表
> 本來我使用這個也是可以出來，但是使用JOIN會比較容易拖垮效能。

SELECT *
FROM `tablename` 
WHERE IndexSn = '5'  
AND `hour` = (SELECT max(`Hour`) FROM `tablename` WHERE IndexSn = '5' );

> 後來強者我同事覺得這樣比較優XDD

## Appendix and FAQ

:::info
**Find this document incomplete?** Leave a comment!
:::

###### tags: `mysql` `MAX`