MySQL

Because heartbeat itself can use dopd to determine if the heartbeat line is down, automatic switching can be realized. However, when some services are down, automatic switching is impossible. Common scenarios include mysqld service, sometimes the

MySQL databaseIt is a synonym for easy-to-use databases. Most database-driven network applications use MySQL as the preferred database, so MySQL has applications on many network servers. Even though the MySQL command statement tool is very useful,

MySQL databaseHow to ImplementMaster/Slave serversWhat about document deployment? How does one perform between master and slave servers?Document SwitchingWhat about it? This article mainly introduces this part of content. Next we will introduce

MySQLDatabaseVarcharWhat is the maximum length? In fact, this is not a fixed number. The length of varchar isRestriction rules. In this article, we will introduce the varchar restriction rules in the MySQL database, and describe the restriction

Linux All operations in the console. Import database: Prerequisites: the database and data table must exist (already created) (1) import the data table test_user. SQL TO THE test_user table of the test database. [Root @ test ~] # Mysql-uroot-p

Explain shows how mysql uses indexes to process select statements and connect tables. It can help you select better indexes and write more optimized query statements. You can add the explain statement before the select statement: For

Use TIMESTAMPDIFF to calculate the time difference between two dates in MySql:Syntax:TIMESTAMPDIFF (interval, datetime_expr1, datetime_expr2)Note:Returns the integer difference between datetime_expr1 and datetime_expr2the. The resultThe unit is

Bad SQL not only directly affects the SQL response time, but also affects the database performance, resulting in a longer response time for other normal SQL statements. It is vital to learn how to write SQL statements and view execution plans. The

I tested it myself. Many characters are changed '? '. The utf8 character set is used for database connection: Copy codeThe Code is as follows:Define ("MYSQL_ENCODE", "UTF8 "); Mysql_query ('set names'. MYSQL_ENCODE, $ conn) or die ('character SET

Recently, I am struggling with how to change the mysql password .. In the wamp environment, left-click your wamp icon. Find mysql under the service, and then you will see a mysql console. You can go to the following steps. Run-> cmd First, we

MySQL databases are IO-intensive programs. Like other databases, their main functions are data persistence and data management. This article focuses on optimizing MySQL database cache parameters such as query cache, table cache, log cache, index

The basic update syntax is to update the table set field = value where field = xxx Existing Material Table materials (y_name, y_quantity), product Table a (p_name, p_quantity), to summarize the materials used by product a to materials Mysql is not

1. Phantom read. Many books and blogs have mentioned that mysql tx_isolate (transaction isolation) is repeatable read. Mysql does next-key lock to prevent phantom read. However, if you use SELECT * from [table];  SELECT * from [table] for

When the data volume is very large (the table capacity reaches GB or TB), if you still use the index method to optimize the query, due to the consumption of the index and the generation of a large number of index fragments, the query process will

Recently, I decided to view the stored procedures written by my colleagues in the past, find some places where the code is not well written, and try to make modifications to make these processes run at a good speed. The following are the most common

Problem SQL Background: if the project has six tables, the corresponding brand_id field should be written according to the pid field. However, there are two tables of tens of millions. After my worker is running, the online mysql master-slave

When querying data in a database, if the data contains a Chinese string, garbled characters may occur during output. before performing the query operation, you can use the set names statement to set the encoding format. Then, no garbled characters

A module in a recent project needs to implement the pinyin initial character query function. I checked the information online and modified the information to meet the project requirements. The implementation process is as follows: 1. Create a

The differences between stored functions and stored procedures are as follows: 1. IN the function parameter list, the mode can only be IN. 2. The function must return a value. Its type is defined in the function header. 3. functions can be called

The DECLARE statement allows us to create variables. It will appear before any cursor and processing in the code block and declaration of any process statement. The syntax of the DECLARE statement is as follows: Common MySQL Data Types