Mysql Group By Desc

I now need to remove the latest content from each category as follows: select * from test group by category_id order by `date` The result is as follows. This is not the data I want, because msyql has the order of execution is the order of reference write: select ... from ... where .... group by ... having ... order by .. Execution order: ...

MySQL large table repeated fields should be how to find it? This is a lot of people have encountered the problem, here is to teach you a MySQL table repeated fields of inquiry, for your reference. The database has a large table, you need to find the name of the duplicate record id, in order to compare. If only to find the name of the database does not repeat the field, it is easy SELECT min (`id`),` name` FROM `t ...

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The complete collection of SQL statement operations deserves to be permanently stored the following statements are part of the MSSQL statement and are not available in Access. SQL classification: ddl-data Definition language (create,alter,drop,declare) dml-Data Manipulation Language (Select,delete,update,insert) dcl-Data Control Language (Grant,revoke, Commit,rollback first, briefly introduce the basic statement: 1, Description: Create number ...

Method 1 delete yourtable where [id] not in (select max ([id]) from yourtable group by (name + value) b on a.id = b.id where b.id ...

Intermediary transaction SEO diagnosis Taobao guest Cloud host Technology Hall log is a very broad concept in computer systems, and any program may output logs: Operating system kernel, various application servers, and so on. 　　The content, size and use of the log are different, it is difficult to generalize. The logs in the log processing method discussed in this article refer only to Web logs. There is no precise definition, which may include, but is not limited to, user access logs generated by various front-end Web servers--apache, LIGHTTPD, Tomcat, and ...

"Guide" the author (Xu Peng) to see Spark source of time is not long, note the original intention is just to not forget later. In the process of reading the source code is a very simple mode of thinking, is to strive to find a major thread through the overall situation. In my opinion, the clue in Spark is that if the data is processed in a distributed computing environment, it is efficient and reliable. After a certain understanding of the internal implementation of spark, of course, I hope to apply it to practical engineering practice, this time will face many new challenges, such as the selection of which as a data warehouse, HB ...