Category：MySql
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Time：2020-7-10
Mysqldump tool backup Back up the entire database $> mysqldump -u root -h host -p dbname > backdb.sql Back up a table in the database $> mysqldump -u root -h host -p dbname tbname1, tbname2 > backdb.sql Backing up multiple databases $> mysqldump -u root -h host -p –databases dbname1, dbname2 > backdb.sql Back up […]
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Time：2020-7-10
#Select the heroes whose Max HP is greater than 6000 and max mana is greater than 1700, and then sort them from high to low according to the sum of the two SELECT NAME , hp_max, mp_max FROM heros WHERE hp_max > 6000 AND mp_max > 1700 ORDER BY ( hp_max + mp_max ) DESC; #Query the hero with Max HP and max mana greater than […]
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Time：2020-7-9
Foreword: today, I want to connect to MySQL on my server remotely. The software used is Navicat. The version of MySQL on the server is 5.7 There was an accident the first time we connected It means that the MySQL service cannot be connected. The solution steps are as follows First: first of all, check […]
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Time：2020-7-9
Transferred from: http://www.maomao365.com/?p=10564Abstract: The following describes how to keep only one data when querying duplicate data in MySQL databaseRealization idea:There is no row in MySQL database_ Number function, so we need to change direction to implement this function. mysql> select * from `maomao365.com`; + | keyId | infoB | + | 1 | mysql test […]
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Time：2020-7-9
Database classification Relational database (SQL): fixed storage and security Non relational database (NoSQL): the storage mode is more flexible, the storage efficiency of data is relatively high, and it is not very safe MySQL is a relational database management system (a database system that uses relational models to organize and manage data) […]
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Time：2020-7-8
Usage of time difference function timestampdiff and DateDiff When we write SQL statements, especially in stored procedures, we will frequently use the comparison and judgment of date and time. Then we will give an example of the usage of these two time difference comparison functions. DateDiff function, the return value is the difference in days, […]
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Time：2020-7-7
Local database connection server database report 1045, how to solve? User “root” @ local host access denied Solution: 1. Find the my.ini The file is opened in the way of Notepad; 2. After opening, find the location of mysqld. There are multiple mysqld in the content of this file. Pay attention to the position indicated […]
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Time：2020-7-7
Screening criteria Comparison operator Equal to: = (note! Not = =) Not equal to:! = or < > Greater than: > Greater than or equal to: >= Less than:< Less than or equal to:<= IS NULL IS NOT NULL Logical operator And: and Or: or Not: not Other operations Order by Positive sequence: ASC Reverse: […]
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Time：2020-7-6
Note: MySQL 5.7 can crack the root password, skip password authentication, log in to the database, and directly change the password in the table, but MySQL 8.0 can’t change the root password like this. After logging in to the database by skipping password authentication, set the root password to blank before you can log in […]
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Time：2020-7-5
MySQL installation, configuration, optimization, for your reference, the specific content is as follows MySQL Download First log in to the official website to download the MySQL installation package and official website address https://dev.mysql.com/ Drop down to the end and select MySQL community server in downloads Select the version you want to download MySQL installation 1. […]
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Time：2020-7-4
Solve the problem of eight hours difference in MySQL insertion time Generally, several parameters need to be added to the JDBC URL, and most of the tutorials given by blogs areuseSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTCThese parameters, The configuration results are as follows:jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC To solve the time zone problem, I used to use servertimezone = UTC. Until today I stepped […]
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Time：2020-7-3
summary UNION By connecting the keywords of the dataset, two query result sets can be spliced into one, and the same records will be filtered out UNION ALL By connecting the keywords of the dataset, two query result sets can be spliced into one, and the same records will not be filtered out Today, when […]
