MySQL

MySQL, database encoding is a very important problem, sometimes we need to look at the current database encoding, and even need to modify the database encoding.The SQL statements that view the current database encoding are:mysql> use xxxdatabase

☆ NOTE: MySQL database installation is not introduced, because everyone installation path is different, so this step ignored, said the focus:1. Initialize MySQL database/usr/local/mysql/scripts/mysql_install_db--user=mysql--basedir=/usr/local/mysql--

First, mathematical functionsABS (x) returns the absolute value of XBIN (x) returns the binary of X (Oct returns octal, HEX returns hex)CEILING (x) returns the smallest integer value greater than XEXP (x) return value E (base of natural logarithm) x

MySQL master-slave configuration for read-write separationLarge web site in order to soft solution a large number of concurrent access, in addition to the site to achieve distributed load balancing, far from enough. To the data service layer, the

I have a tableCREATE TABLE ' Tablemain ' ( ' id ' int (one) not null auto_increment, ' value1 ' varchar "not NULL, ' value2 ' Varc Har (not NULL, ' value3 ' int is not NULL, ' value4 ' timestamp not null, ' value5 ' int not nullprimary

2015-10-24DirectoryResources[1] Tang Hanming. mysql database development, optimization and Management Maintenance (2nd edition) [M]. Beijing: People's post and Telecommunications press, 2014[2] Schwartz. High-Performance MySQL (3rd edition) [M].

#!/bin/bash#/usr/bin/nmap localhost | grep 3306#lsof-i:3306mysqlport= ' Netstat-na|grep "LISTEN" |grep "3306" |awk-f[: ""]+ ' {print $} 'function Checkmysqlstatus () {/usr/bin/mysql-uroot-paaaaaa--connect_timeout=5-e "show databases;" &>/dev/null 2>&

The Java connection MySQL database method under Linux system is similar to that under Windows, the following steps are as follows:Download JDBC (driver): mysql-connector-java-5.1.37.tar.gzUnzip the downloaded packet: TAR-ZXVF mysql-connector-java-5.1

1,MySQL ignore the primary key conflict, avoid the repeated insertion of several ways.2, set the MySQL connection timeout parameter can refer to: One, two or three.3 . Check the current number of MySQL connections.1), View status:SHOW STATUS;2),

Recently in the project development, there is a logic processing, need to run in the website, app, backstage, so that the maintenance of the late to bring a lot of inconvenience, easy to omit the app side or the background, so the Java code to

This is the first article in the blog park, because I am still a programming rookie, also can not write those tall on the great article, this article is on their own this time to learn python a summary of it.It is well known that Python is a very

Python's MySQLdb module is a python-connected MySQL module, and the default query results are returned as a tuple type, which can only be accessed through 0,1. Index Access dataDefault Connection database: MySQLdb.connect (Host=host, User=user,

PackageCn.itcast.demo2;Importjava.sql.Connection;ImportJava.sql.DriverManager;ImportJava.sql.ResultSet;Importjava.sql.SQLException;Importjava.sql.Statement;Importorg.junit.Test; Public classDemo2 {/** Connect database, get connection even success! *

Let's start with an example:#建表DROP TABLE IF EXISTSt_attendance;CREATE TABLEt_attendance (Job_noVARCHAR( -)DEFAULT "', OperatetimeVARCHAR( -)DEFAULT "', INDEXIndex_operatetime (operatetime),INDEXindex_jobno (Job_no)) ENGINE=INNODBDEFAULTCHARSET=utf8

if AB different steps1) View the auxiliary SQL log tailf/var/log/mysqld.log140304 11:59:18 [Note] Slave I/O thread:connected to master ' [email protected]:3306 ', replication started in log ' Binlog .000011 ' at position 294# whether the server can

1. It's a good idea to index fields that you use frequently (for example, often to sort by these fields or to search) . 2, the type of the field as far as possible with int or tinyint types. In addition, the field is used as NOT null 3, of course,

1. Select-union (Joint Enquiry)The union is used to combine the results from many SELECT statements into a single result set. Usage:SELECT ... UNION [All | Distinct]select ... [UNION [All | Distinct]select ...] 2. Introduction of Select-union (joint

1. Requirements:The number of substitute teachers in class 0115 was obtained, the results were sorted by ascending order, and 0228 classes were obtained, and the results were sorted in descending order. (1) first check the originalclass 0115

Gcc-g Mysqlquery.c-lmysqlclient-i/usr/include/mysql-l/usr/lib64/mysql#include #include#includestring.h>#include#includeintMain (intargcChar*argv[]) { if(ARGC 2) {printf ("a.out sql\n"); } MYSQL Conn; Mysql_init (&conn); if(! Mysql_real_

1. LAST_INSERT_ID:LAST_INSERT_ID is not related to table, last_insert_id will change if data is inserted into table A, and then the data is injected into form B.LAST_INSERT_ID is based on connection, as long as each thread uses a separate connection