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Single table query Basic format select [ all | distinct ] selection_list from table_score [where search_condition] [group by grouping_colums] [with rollup] [having search_condition] [order by order_expression [asc \ desc]] --asc ascending, desc descending [limit count] - limit the output result line of query   SQL select_expr Alias ...

Why is there such a need Recently, we have an online project. Due to the large amount of read-write data, the pressure on the database increases, so now we plan to adopt the scheme of read-write separation. How to solve it The framework we use is springboot+mybatisplus, and it is an online project. It can not be transformed in large quan ...

preface Today, I'd like to introduce a commonly used Squid log analysis software to you. I hope it can be used by helpful students in their daily work in the future. Sarg: full name: Squid Analysis Report Generator, is a Squid log analysis tool, which lists the Internet website information, time occupation information, ranking, connection tim ...

1, Single line function 1. Character function 1.1 length gets the number of bytes of the parameter value SELECT LENGTH('john'); --'4' SELECT LENGTH('Huo Yuanjia lalala'); --'15' 1.2 concat splice string SELECT CONCAT(last_name,'_',first_name) full name FROM employees; 1.3 # upper and lower change the string to uppercase or lowe ...

Pithy formula: find my CNF, error finding Log. Find slow log 1, Database configuration file 1.my.cnf file my.cnf is the configuration file loaded when mysql is started. It is usually placed in the mysql installation directory. Users can also load it in other directories, usually in / etc / my cnf. MySQL configuration file has m ...

I used to use the SQL server under win. I'm a little unfamiliar with MySQL. I may introduce some basic information. If there is any incorrect description, I'd like to ask the boss for advice The relationship between the twoInstall MySQLInstall MariaDB (one line installation)Simple daily use The relationship between the two MariaDB and My ...

docker official website: https://docs.docker.com/samples/wordpress/ Introduction to WordPress You can use Docker Compose to easily run WordPress in an isolated environment built with Docker containers. This quick start guide demonstrates how to use composition to set up and run WordPress. Before you begin, make sure you have installed aut ...

Self use notes, combined with crazy God talk videos and official documents, were written in May 2021. Mybatis plus is updated quickly and may fall behind in the future. Only share for reference brief introduction concept MyBatis plus is an enhancement tool of MyBatis. Based on MyBatis, it only makes enhancement without change, and is b ...

1, Experimental time June 1, 2021 - June 30, 2021 2, Experimental preparation In the experiment, you need to buy an instance on Huawei cloud database, create a corresponding table, and import the corresponding data. The specific data is given in the teacher's Excel table. For the specific process of purchasing and building tables, please ...

14, SQL optimization tool 1. Slow query log MySQL's slow query log is a kind of log record provided by mysql. It is used to record the statements whose response time exceeds the threshold in MySQL. Specifically, it refers to the statements whose running time exceeds long_ query_ SQL with time value will be recorded in the slow query log. long_ ...