mysql two counts in one query

DongdongzzcsThe 1th page:"IT168 Zhuangao" the author of this article, Daniel Nichter, is the developer of the MySQL tool, who recommended 10 essential tools for MySQL administrators. The following is the full text content:MySQL is a complex system

This article is "high-performance MySQL" Reading notes Slow Query Basics: Optimizing data accessThe most basic reason for poor query performance is that there is too much data to access. For inefficient queries, we found that the following two

mysql| Reference | Reference Manual | cache | Chinese MySQL 4.1.0 chinese reference manual---dog (heart sail) Translate MySQL Reference Manual for version 4.1.0-alpha. 6.9 MySQL Query Cache Starting with MySQL 4.0.1, MySQL server has an

Query performance optimizationWhy is the query slower? The life cycle of a query can be roughly in order: from the client to the server, then parse on the server, generate execution plans, execute, and return results to the client. In the execution

This article transferred from: HTTPS://WWW.TUICOOL.COM/WX/2EMBFMQObjectiveTalking about MySQL query optimization, I believe you have a collection of artifice: You cannot use SELECT *, do not use null fields, reasonably create an index, select the

MySQL server has an important feature since MySQL 4.0.1: Query Cache. In use, the query cache storesSELECTThe query text corresponds to the result sent to the client. If the same query is received later, the server will retrieve the result from the

This article describes how to analyze MySQL slow query logs by setting parameters to analyze the causes of performance problems, for more information, see query. Currently, most databases provide performance analysis tools. For example, Oracle will

MySQL query data table data record (including multi-table query) MySQL query data table data record (including multi-table query)Transferred from: http://www.baike369.com/content/?id=5355The purpose of creating a database in MySQL is to use

MySQL optimization-performance analysis and query optimizationoptimization should be carried out throughout the product development cycle, such as when writing complex SQL to view the execution plan, when installing the MySQL server as reasonable as

MySQL Query Cache Query_cache_size Starting with MySQL 4.0.1, MySQL server has an important feature: Query Cache. When in use, the query cache stores the text of a SELECT query and the corresponding results that are delivered to the client. If you