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關(guān)于mysql優(yōu)化的問(wèn)題

修改問(wèn)題: 下面出現(xiàn)的問(wèn)題貌似是我本地環(huán)境的問(wèn)題, 換了個(gè)環(huán)境就可以了, 現(xiàn)在我想問(wèn)問(wèn)我的環(huán)境為什么會(huì)出現(xiàn)下面的情況 :(最近學(xué)習(xí)數(shù)據(jù)庫(kù)優(yōu)化, 遇到不少不解的地方:mysql查詢(xún)數(shù)據(jù)時(shí)filesort什么情況下出現(xiàn),&n...

From [MySQLdiscussion group] 2016-11-19 13:29:09 0  1  865

php - mysql multi-table query

There are two tables, briefly describe them. Table 1: Relationship table between courses and students rsid cid...

From [MySQLdiscussion group] 2017-05-25 15:08:10 0  3  864

c# - mysql query optimization?

1. There are more than 1 million pieces of data. The count speed is very slow. Please let me know how to optim...

From [MySQLdiscussion group] 2017-05-18 10:51:56 0  5  864

mysql - navicat 經(jīng)常打開(kāi)表一直在載入中 也不能關(guān)閉 著急解決

navicat 經(jīng)常打開(kāi)表一直在載入中 也不能關(guān)閉 著急解決

From [MySQLdiscussion group] 2017-04-17 16:44:09 0  2  864

mysql - Read_Master_Log_Pos 比Relay_Master_Log_File的最大位置要大怎么辦？

如題：MySQLRead_Master_Log_Pos 比Relay_Master_Log_File的最大位置要大怎么辦？

From [MySQLdiscussion group] 2017-04-17 11:08:54 0  0  864

導(dǎo)入數(shù)據(jù) - mysql如何導(dǎo)入null到float字段

用load data的方式導(dǎo)入CSV文件，其中一列數(shù)值類(lèi)型是float，但存在一些空值，導(dǎo)入后mysql默認(rèn)將空值設(shè)為0了，該如何解決？目的是想存空值

From [MySQLdiscussion group] 2017-04-17 13:45:40 0  2  863

mysql - 要取出數(shù)據(jù)庫(kù)中按某字段排序后的前10，20，30條數(shù)據(jù)要怎么做？

要取出數(shù)據(jù)庫(kù)中按某字段排序后的前10，20，30條數(shù)據(jù)要怎么做？表中這樣的字段有很多。因?yàn)橛卸鄠€(gè)排行榜。比如有totalClickNum，monthClickNum，weekClickNum等。對(duì)數(shù)據(jù)庫(kù)操作不是很懂。具體...

From [MySQLdiscussion group] 2017-04-17 15:04:32 0  3  862

mysql - 論壇帖子排序問(wèn)題

先上圖 目的：查詢(xún)出所有的帖子，將評(píng)論最多的3個(gè)排前面，其余再讓更新帖子時(shí)間排序，我自己寫(xiě)的（如圖，始終按評(píng)論[count_comment] desc）了 ，達(dá)不到我要的效果 ，應(yīng)該怎么改？？？

From [MySQLdiscussion group] 2017-04-17 16:07:11 0  2  861

數(shù)據(jù)庫(kù) - 為什么MSSQL和MYSQL那么的不統(tǒng)一?

目前一個(gè)項(xiàng)目需要將愿數(shù)據(jù)庫(kù)(sqlserver)中的數(shù)據(jù)取出并做一定處理后存入目標(biāo)數(shù)據(jù)庫(kù)(mysql),但是mssql和mysql無(wú)論是sql語(yǔ)句還是內(nèi)置函數(shù)很多地方都不統(tǒng)一(比如mysql的自增是auto_increm...

From [MySQLdiscussion group] 2017-04-17 14:18:33 0  3  861

Workaround: How to resolve Unable to delete or update parent row: Foreign key constraint violated?

I want to delete users based on phone number. So I made a custom query to delete that specific user. But an er...

From [MySQLdiscussion group] 2024-03-25 18:47:47 0  1  860

Mysql under Mac does not support Chinese and the configuration file does not have a my-default.cnf file

1. My mysql does not support Chinese. I followed the online method to change the encoding, but I cannot find t...

From [MySQLdiscussion group] 2017-05-18 10:52:03 0  2  860

mysql優(yōu)化 - MySQL中使用UNION進(jìn)行兩表合并，去重導(dǎo)致效率低下，請(qǐng)問(wèn)如何優(yōu)化？

如下SQL語(yǔ)句在MySQL中執(zhí)行需要2秒左右的時(shí)間，如果使用UNION ALL進(jìn)行不去重合并只需要0.4秒，UNION ALL配合DISTINCT來(lái)去重速度又變成2秒了，請(qǐng)問(wèn)如何進(jìn)行優(yōu)化？ {代碼...}

From [MySQLdiscussion group] 2017-04-17 14:48:54 0  3  860

mysql optimization gender optimization

There are hundreds of thousands of users in the database, 90% of whom are men. Sex = 1. For example: select ui...

From [MySQLdiscussion group] 2017-05-18 10:51:08 0  3  859

Unable to insert values ??into mysql database using spring boo

Hibernate: Inserting employee (age, name) values ??(?,?) I don't know how to fix it, I tried everything but un...

From [MySQLdiscussion group] 2024-03-22 13:11:21 0  1  858

How to implement decreasing balance using MySQL

How to create a declining balance query using mysql to calculate depreciation in accounting. For example, equi...

From [MySQLdiscussion group] 2023-09-01 21:11:53 0  1  858