MySQL

date_format (DATE, FORMAT) function usageThe Date_format (date, format) function formats the date value according to the format string.1. Convert a string to a date formatInstance:SELECT Date_format ('2017-09-20 08:30:45', '%y-%m-%d%h:%i:%s'

In some cases, the value of some fields in the data table will appear with a white-space character if the program is not handled properly, asThis will not match if it is strictly compared to name. The trim () function solves this problemAs a subset

A transaction is a series of operations that are performed as a single logical unit of work that is submitted to the system as a whole, either executed or not executed. A transaction is an inseparable unit of work logic.Transactions have four

Just installed superset When everyone knows it is used automatically generated Sqllite database, if we want to let the device link to their own database, to share my approach to MySQL, for example:1. Install the database MySQL:$ sudo apt-get install

One requirement for recent projects is to limit the number of operations logs to 100,000, and more than 100,000 to delete the oldest one, saving no more than 100,000 of the logs in the database.My first thought was to do it through a trigger and

1. A convenient use of the while loop is to loop through the rows of data in a SQL query result.2, Mysqli_fetch_array (), this built-in PHP function gets a data row from the result of a database query, which can be paired with while repeatedly

MySQL Installation Method:(1) RPM Mode: RPM package is a Linux platform installation files, MySQL RPM installation file package is divided into two, that is, the server side and the client, need to download the installation separately(2) Binary

Mysql master-slave Mechanism Mysql master-slave replication Principle 1) on the mysql master database, the changes are recorded in the binary log. 2) on the mysql slave database, the IO thread copies the binary log in the mysql master database to

Mysql Stored Procedure example /*Define VariablesMethod 1: set @ variable name = value;Method 2: select value into @ variable name;Method 3: default Value of the declare variable name type (string type plus range; The value of the in parameter will

Summary of daily management commands of mysqladmin in mysql (mandatory), mysqlmysqladmin Format of mysqladmin tool:Mysqladmin [option] command [command option] command ...... Parameter options: -C number indicates the number of automatic runs, which

Explain SQL efficiency and explain SQL Efficiency The Explain command is the first recommended command for solving database performance. Most performance problems can be solved simply by using this command. The Explain command can be used to view

Mysql uses init-connect to add the implementation of the access audit function, mysqlinit-connect Mysql is first initialized through init-connect and then connected to the instance. We use this to record the user's thread_id, user name, and user

Mysql order by in (recommended) and mysqlorder // MySQL statement SELECT * FROM 'mytable' WHERE 'id' IN (111, 111) order by field ('id ); Laravel framework $ Ids = array (1, 17, 2); $ ids_ordered = implode (',', $ itemIds); $ items = static:

MySQL Partition Table limitations and restrictions Build prohibited Partition expressions do not support the following types of construction: Stored Procedures, stored functions, UDFS, or plug-ins Declare variables or user Variables See SQL

How to change the root password of mysql in Linux: mysqlroot Preface It may have been several months since the service was deployed in mysql. Because the current work is basically on the terminal, it is very rare to log on. Today, I want to modify

Innodb Engine redo file maintenance method, innodb Engine redo Maintenance To adjust the size and number of redo log files of innodb, follow these steps: 1. Disable mysql Mysqladmin-h127.0.0.1-P3306-uroot-p shutdown 2. Modify

Detailed description of MySql slow query analysis and enabling slow query log, detailed description of mysql enabling log I am also studying MySQL performance optimization recently, so I will take a study note today! In projects developed by our

MySql 5.7.17 installation-free configuration tutorial details, 5.7.17 installation and configuration tutorial 1 download mysql-5.7.17-winx64.zip installation package (link: https://dev.mysql.com/downloads/mysql) 2. Unzip the installation package. D:

Detailed description of mysql row-to-column and column-to-row instances, mysql instances Mysql row-to-column and column-to-row It is not difficult to explain the statement. When you look at the statement, explain the sentence from the inside

Mysqldump instances and mysqldump instances are excluded from database backup. Note: Use mysqldump-all-databases to export all databases. However, if the master node dumps data from the master database, we do not need or want information_schema or