MySQL

mysql5.5 version and version 5.6 on the same server to open the instance, in daily work will encounter, open multi-version need to note:1. Startup initialization cannot be initialized with the name of the Ln-s link.2, start need to

1. Uninstall the previously installed MySQL serviceCheck the registry hkey_local_machine\system\controlset001\services\mysql, some words delete the item, then return to cmd inside output mysqld--remove Enter, the service Successfully removed.

[[Email protected] -desktop]# Mysql-uroot-Penter Password:welcome to the MySQL Monitor. Commands End With; or \g.your MySQL connection ID is 3Server Version:5.6. -Copyright (c) -, ., Oracle and/or its affiliates. All rights reserved. Oracle isA

I've always felt a lot of trouble installing MySQL under Linux because it was a bit dizzy when it was installed because of a complicated configuration. Today, you need to connect MySQL with QT under Linux. The installation is equipped with a set.1)

Today the database load goes straight up and the number of database connections explodes. Take a look at the sentence, the culprit is a very simple statement: SELECT * from Eload_promotion_code WHERE 1 and exp_timeFirst look at the index of this

Today the database load goes straight up and the number of database connections explodes. Take a look at the sentence, the culprit is a very simple statement: SELECT * from Eload_promotion_code WHERE 1 and exp_timeFirst look at the index of this

ConstraintsRole: Ensure data integrity, uniquenesscolumn-level constraints (used for 1 fields) based on fields: table-level constraints (used for 2 or more fields)Constraint type: NOT NULL non-null constraintPRIMARY Key PRIMARY KEY constraintUnique

The business needs to be implemented simultaneously:Update HYDYGX Set state = "n" where User_id=1 and friend_id in (2,3,4);Update HYDYGX Set state = "user_id" in (2,3,4) and friend_id = 1;We all know that since it is a two-sentence UPDATE statement,

To modify the MySQL configuration file my.cnf, the contents are as follows:[Mysqld]Datadir=/data/mysql/dataSocket=/var/lib/mysql/mysql.sockUser=mysql# Disabling Symbolic-links is recommended to prevent assorted security risksSymbolic-links=0# Set

MySQL's binlog detailedWhat is BinlogThe Binlog log is used to record all statements that have updated data or that have potentially updated data (for example, a delete that does not match any row). Statements are saved as "events," which describe

1. Three threads: Main Library binlog dump thread, from library I/O thread and SQL thread. 2.creation Process: When replication starts from the library (start Slave), you first createI/Othreads Connect to the main library, and the main library then

There are two ways to set a foreign key, one to associate a foreign key when creating a table, and another to add a foreign key to a table that already exists. Here's how:1. Actions when creating a tableClass table (Main Table):CREATE TABLE TB1 (ID

MYSQLL provides a mysqldump command that we can use to back up data.Follow the prompts to enter the password, this will be the ABC database all the table structure and data back to Abc_20161108.sql,# mysqldump-u ROOT-P ABC > Abc_20161108.sqlBecause

MySQL 4.1 is MySQL323 encryption, MySQL 4.1 and later versions are MySQLSHA1 encrypted,(1) Encrypt in MySQL323 modeSelect Old_password (' 111111 ');(2) Encrypt in MySQLSHA1 modeSelect password (' 111111 '); MYSQL323 encryption is generated in a

MySQL turns off batching by default, so we store 10,000 of data in the database by default (batch is not open), with the following core code:

For MySQL, each step will have a corresponding record, such as insert,update,delete, DROP, alter and other related DDL or DML operations. Sometimes it's hard to make mistakes, but how to recover the data when something goes wrong.For example, you

Select U.username,date_format (c.create_date, '%y-%m-%d ') createdate,date_format (c.create_date, '%y-%m ') createdate,COUNT (*) SummerFrom nb_custom C, nb_user uwhere 1=1 C.create_date >= #{startdate} C.create_date and u.username=#{usernametj}

Basic concepts of SQL-commands and basic concepts of SQL 1, MySQL(Structured query language) standard language 2 for accessing and processing Databases What is SQL?SQL refers to the structured query language. SQL enables us to access databases

Basic mysql operation Study Notes (2) ---- index, mysql Study Notes Why create an index? With the same question, I can only explain that the speed required for database query is reduced. If the time difference between a normal query and an index

MySQL uses if and mysqlif to determine Select *, if (sva = 1, "male", "female") as ssva from taname where sva <> "" 12.2. Control Flow FunctionsCASE value WHEN [compare-value] THEN result [WHEN [compare-value] THEN result...] [ELSE result] end case