MySQL

The advantages of the index 1, the index can greatly reduce the amount of data the server needs to scan 2, the index can help the server avoid sorting and temporary tables. 3, the index can turn I/O into sequential I/O Second, indexing strategy

I. Pitfalls in Design 1, too many columns The MySQL storage Engine API works by copying data between the server layer and the storage engine layer through a row buffer format, and then decoding the buffered content into columns at the server layer.

1, understand the MySQL program path MySQL Data directory:/home/mysql/data MySQL Program directory:/USR/LOCAL/MYSQL5 2, modify the MySQL service startup program [root@lyq314 ~]# Vim/usr/local/mysql5/share/mysql/mysql.server

0. Installation CMake [root@lyq314 ~]# TAR-ZXVF cmake-2.8.11.2.tar.gz [root@lyq314 cmake-2.8.11.2]#./configure [Root@lyq314 cmake-2.8.11.2]# make [root@lyq314 cmake-2.8.11.2]# make install 1, add MySQL users and groups [root@lyq314 ~]

A character set is a mapping from binary encoding to a type of character symbol, and can refer to how to use a byte to represent English. Proofing refers to a set of collations that are used for a character set.Each type of encoded character has

At work, there is a need to count 24 hours of relevant data. Some friends think that a simple group by can be solved. In fact, the real statistics, 24 hours have to have data, do not allow the absence of the phenomenon. Actually this is a bit like

If you never set the root user password for MySQL, the server does not need a password to connect as root. However, it is recommended that you set a password for each account. If you have previously set the root user password, but have forgotten

1. #!/bin/sh 2. Cd/home/mysql-backup 3. RM alldb.5.tar.gz-f 4. MV Alldb.4.tar.gz Alldb.5.tar.gz>/dev/null 2>&1 5. MV Alldb.3.tar.gz Alldb.4.tar.gz>/dev/null 2>&1 6. MV Alldb.2.tar.gz Alldb.3.tar.gz>/dev/null 2>&1 7. MV Alldb.1.tar.gz Alldb.2.tar.gz>/

If you have recently made a select or update query, you may have used one or more MySQL comparison operators to limit the query's output. Comparisons are an integral part of most select queries, and MySQL provides many functions for this function;

ALTER TABLE changes the table to the current character set. If a duplicate key error is encountered during the execution of the ALTER TABLE operation, the new character set maps 2 keys to the same value or the table is corrupted. In the latter case,

1. Hardware environment: 　　 Hard disk: 9.2 G; Memory: 128 M; Network card: EEpor100 　　 2. Software 　　 Operating system: RedHat 6.2 　　 3. Optimize Redhat 6.2 　　 Select when installing FTP and DNS 　　 Edit File/etc/hosts 　　 To 202.104.131.

The following article mainly describes the MySQL select Use techniques, MySQL select in the actual proportion of the application is still accounted for, if you are curious about this new development of technology, the following article will uncover

Starting with the MySQL 5.0.2, the server-side cursor is implemented through the Mysql_stmt_attr_set () C API function. The server-side cursor allows the result set to be generated on the server side, but is not transferred to the client unless the

A station may experience gb2312 (GBK,BIG5) to UTF8 conversion process, which will encounter a lot of problems. The site is too big how to do it, can only step by step. It would be much easier to complete the conversion of the data first, with

1. Add the configuration information in the $catalina_home/conf/server.xml, declare the specific information of the connection pool, add the following

When you first install and run MySQL, you may encounter some errors so that the MySQL server does not start. The purpose of this section is to help you diagnose and correct these errors. Your first information when troubleshooting server problems

Installing MySQL is unsuccessful, typically because the server may have installed MySQL without a full uninstall. If you encounter MySQL can not start the following situations: whether double-click mysqld.exe or use the command line, are not

Case problems when you perform a lookup command By default, MySQL does not differentiate between uppercase and lowercase when performing a lookup. When you use like ' a% ' on a lookup, the default returns all column values starting with a or a, and

As we know, there are four transaction isolation levels in the relational database standard: Uncommitted read (READ UNCOMMITTED): Allow dirty reads, that is, data that may be read to uncommitted transaction modifications in other sessions Commit

Utility to dump a database or many databases for backup or to transfer data to another SQL Server. Dumping will include SQL statements that create tables or enrich tables. shell> mysqldump [OPTIONS] database [tables] If you do not give any tables,