MySQL

Java connection MySQL Tutorial data code Package jxc; Import java.sql.connection;Import Java.sql.drivermanager;Import java.sql.preparedstatement;Import java.sql.ResultSet;Import java.sql.sqlexception;Import java.sql.statement;Import java.sql.*;

The following is an example of the database "Ceshi" 1, connect the database The code is as follows Copy Code Mysql-u username-p Password 2. Create/Delete Database The code is as follows Copy

Using on DUPLICATE KEY update Look at two SQL first The code is as follows Copy Code INSERT into Osc_visit_stats (stat_date,type,id,view_count) VALUES (?,?,?,?) On DUPLICATE KEY UPDATE view_count=view_count+?

MySQL serve is 5.1.x, the client is 5.0.x, with phpMyAdmin, there is always a hint that the version does not match, feeling bad. Use the Ports method to upgrade the client, no, no error. Said 5.1 and 5.0 conflict, can only be deleted first.

Restore a database: mysql-h localhost-u root-p123456 Www Back up a database: mysqldump-h localhost-u root-p123456 www > d:/www2008-2-26.sql Backup data: The code is as follows Copy Code Mysqldump-u User name-p password

Re-edit the encoding First copy a my.cnf to/OPT/LOCAL/ETC/MYSQL5: The code is as follows Copy Code $ cd/opt/local/etc/mysql5/$ sudo cp/opt/local/share/mysql5/mysql/my-small.cnf my.cnf Then edit my.cnf and add

Solve the problem of garbled web pages, defined in the program query The code is as follows Copy Code db = MySQL _connect ("localhost", "User", "password");mysql_select_db ("message", $db);mysql_query ("SET NAMES ' UTF8 '

Mysqldump Export Command Base usage The code is as follows Copy Code Mysqldump-u username-P [--opt] DATABASENAME [Table] > Export SQL file name The default mysqldump exported SQL file contains not only the

COUNT (*) calculates the number of rows, including null Count (column) calculates the number of rows for a particular column's value, and does not contain null values. Count () is also used, and the use of Count (1) is the same as the result of

The following query selects all records and its date_col value is within the last 30 days: The code is as follows Copy Code Mysql> SELECT something from tableWHERE To_days (now ())-To_days (Date_col) DayOfWeek

One, time lag DateDiff: To put it bluntly is to use the first time to reduce the second time, the order can not forget The code is as follows Copy Code Select DateDiff (' 2012-08-08 ', ' 2012-08-13 '); ---5

First, the way to start 1, use service to start: Service mysqld start 2. Start with mysqld script:/etc/init.d/mysql start 3. Use Safe_mysqld to start:safe_mysqld& Second, stop 1, use service to start: Service mysqld stop 2. Start with mysqld

On Weibo, see @ Jinshan mentions a performance problem in MySQL, The code is as follows Copy Code Select ID from table where ID > M ID Which is faster? There are three kinds of query conditions here:

Backup data: The code is as follows Copy Code Mysqldump-u User name-p password database name > Xx.sql When the volume of data is large, you can use gzip compression The code is as follows Copy

There are 2 ways to resolve this problem: localhost change to% Go to MySQL Bin directory The code is as follows Copy Code Mysql-u root-pMysql>use MySQL;Mysql>update User Set host = '% ' where user = ' root

Compare with mysqldump: 1, the former is a fast file in the sense of copy, the latter is a database-side SQL statement collection.2, the former can only run in the database directory on the machine, the latter may be used in remote clients, but the

Symptoms of damage A typical symptom of a damaged table is as follows:1. When selecting data from a table, you get the following error: Incorrect key file for table: ' ... '. Try to repair it2. The query cannot find rows in the table or return

MySQL Query Cache defaults to open. To a certain extent can improve the effect of the query, but not necessarily the best solution, if there are a large number of modifications and queries, due to the cache failure caused by the modification, the

LTrim function The code is as follows Copy Code Mysql> Select Concat ('. ', LTrim (' ddd '), '. '); RTrim function The code is as follows Copy Code Mysql> Select Concat ('. ', RTrim

$ Hostname = "localhost"; // defines the name of the connected mysql server$ Username = "root"; // defines the user name used for connection.$ Password = ""; // defines the password used for connection.$ Link = mysql_connect ($ hostname, $ username,