MySQL

1 ImportJava.sql.*; 2 3 Public classmysqltest4 { 5 Public Static voidMain (string[] args)throwssqlexception,classnotfoundexception{6 //TODO auto-generated Method Stub 7 8String url = "Jdbc:mysql://localhost/xh"; 9String

MySQL database does not conform to the SQL standard a lot of places, such as timestamp column processing, string comparison default case is not sensitive or anything.Sometimes these problems can make you depressed, especially for those who turn from

In MySQL, sometimes when we are doing database queries, we need to get a record of a certain value in a field, but it is not solved with like, we can find the record that we do not want, and it is more accurate than the find_in_. The set function

MySQL binary log is also a record of some MySQL command operationsTo delete binary log information:The binary log logs a large amount of information (which contains some useless information). If you do not clean up the binary log for a long time,

Four characteristics of transactions (ACID)Atomicity (atomicity)Atomicity means that a transaction is an inseparable unit of work, and the operations in the transaction either succeed or all fail. For example, the SQL statement in the same

1. Basic Enquiry: (1) I only want to query a column of a table: SELECT col1,col2 from table1 filter out the column fields; (2) When I want to query the information of a row: use where col1=1 and col2=2 to filter out the rows; (3) We can use GROUP by

The server quit without updating PID file (/usr/local/mysql/data/mysql.pidThis error almost swept all MySQL startup error;Check the SQL error logInnodb:to Fix the problem and start mysqld:INNODB:1) If There is a permission problem in the file and

Sorting results in slower performanceOptimization strategy: 1. Try not to use sort 2. Only the results of the index are checked and the internal connection querySelect bizchance0_.* from Biz_chance bizchance0_, Biz_bizcustomer bizbizcust1_where

What is a viewA view is a table that is presented from one or more tables and is a virtual existence.A view is like a window through which you can see the data that is specifically provided by the system.This allows users to take care of data that

1.master.info fileLocated at the slave end of the data directory, storage slave connected to master information, such as the master host address, connection user, password, port, the log information has been obtained.The Master.info file is modified

1. Installation and compilation dependenciesYum install-y Libaio libaio-devel cmake ncurses-devel perl2. Compile and installcmake-dcmake_install_prefix=/usr/local/mysql-dmysql_unix_addr=/usr/local/mysql/mysql.sock-ddefault_charset=

The following summarizes some of the most common examples of SQL optimization, although relatively simple, but very practical, I hope to be helpful to everyone. SQL optimization is generally divided into two categories, one is the optimization of

Internet companies generally choose MySQL, which is widely used in the Internet, but have been using Microsoft's stuff, including databases (MS SQL Server).This is not the thought of switching databases so easy, but there are some details to

Be sure to remember reset before restoring from the library, because restarting MySQL does not affect the replication process, and if you forget reset, it will cause you to recover while the main library has actions to write from the library, when

1. Install MySQL Firstsudo Install mysql-serverapt-get isntall mysql-clientsudoinstall Libmysqlclient-devCheck whether the installation was successful:sudo grep MySQLIf you see a socket with MySQL in the Listen state, the installation is

1. Type of index (six types)Normal index, unique index, full-text index, single-column index, multicolumn Index, spatial index2. Advantages and disadvantages and precautionsPros: With indexes, you can increase query speed for tables with a large

Knowledge Preparation:1. What is the query-cache of MySQL?MySQL can cache the execution of the SELECT statement and the result set corresponding to the SELECT statement, and return the result directly the next time the same SELECT statement is

1. Copy the referenced table:CREATE TABLE clone_product_1 like product_1;INSERT into Clone_product_1 SELECT * from product_1;2. Copy the reference table:1. Get the complete structure of the data table.2. Modify the data table name of the SQL

Mysql Data Object Objective:   Understanding common database objects Learn how to create specific data objects What are common mysql Data Objects: DataBase/Schema Table Index View/Trigger/Function/Procedure Multi-Database usage: Business

Summary of how MySQL is disabled on Linux, linuxmysql There are many MySQL startup methods. Some differences and features of these methods are compared and summarized below. The following experiment version is MySQL 5.6. If any omissions or