MySQL

In MySQL, the query string in an integer field returns all results of 0 and should return null or NULL.For example, table structure information:CREATE TABLE ' t ' (' name ' char () COLLATE utf8mb4_unicode_ci default NULL, ' ID ' int (one-by-one) not

Transferred from: http://www.cnblogs.com/gzgccsu/archive/2013/01/23/2873598.html1. What is the use of slow queries?It records all SQL statements that execute more than long_query_time time, helping you to find SQL that executes slowly, so we can

      Today in Ubuntu and CentOS, with the source repeatedly installed many times MySQL, before you forget, hurriedly write down ...       The installation process in Ubuntu and CentOS is no different.      0. Download the source code and upload it

One, DQL statements1. Constant columnSELECT' Studentname ' as the name,' Address ' as,' Beijing Information Center ' as school nameFrom ' student ';2. Common functionsAggregation functionsAVG () averaging pointsCOUNT () Statistics Record countSELECT

First, download MySQL databaseWe're going to download it in version 5.7.This is a 32-bit computer: Https://dev.mysql.com/get/Downloads/MySQL-5.7/mysql-5.7.18-win32.zipThis is a 64-bit computer: Https://dev.mysql.com/get/Downloads/MySQL-5.7/mysql-5.7.

Causes of master-slave replication delays:(1) The main library is too many from the library, causing replication delays(2) The difference from the library hardware compared to the main library, resulting in replication delay(3) too many slow SQL

With master-slave replication, it is also necessary to do regular full and incremental backups, because the master-slave is synchronous, that is, if the main library deleted a library, from the library will also delete a library, so if you want to

First, the configuration MySQL Database1, unzip the green version of MySQL, such asSecond, installation Services1, run cmd (Administrator version, otherwise no permissions), such as2, run the command Mysqld–install installation Services, such as:If

Recently the boss gave a demand, is to write a name of fuzzy query.The problem is simple, the difficulty is that the table has nearly 500W data.If you want to do Chinese fuzzy query, the efficiency is simply appalling.I looked up the information on

1. Download the corresponding MySQL installation source code packageAddress: http://dev.mysql.com/downloads/mysql/5.1.html2. If you have ever installed, uninstall the unused old installed MySQLBecause there are a lot of Linux distributions, the

Background:MySQL often encounters too many open files,mysql on the Open_files_limit and OS level set on the open file limit what is the relationship?The source code will also see different data structures, table, Table_share, and what is the

The INFORMATION_SCHEMA database is the MySQL system's own database, which provides access to the database metadata. Feeling information_schema is like an encyclopedia of MySQL instances, which records most of the information we need to close in the

1. Download and install MySQL, because open source free, directly to the official website to download and follow the prompts to install: https://www.mysql.com/downloads/2. After the installation is complete, see if the process has MySQL enabled

MySQL base ——— data type Integer type: Depending on the range of values that are stored for the integer value, it can be divided into the following five categories: (1）tinyintoccupies 1 bytes (2）smallintoccupies 2 bytes (3) Mediumint of 3 bytes

Recently try to install MySQL in My computer so the I can practise some SQL statement on sever. But there is some problem while the install MySQL package in my Ubuntu system. I Hava tried lots of ways to move on. At the last. I Find There is

1. In the command line, type NET Start/stop mysql on/off MySQL service2. Type the Mysql-u user name-p password in the command line to connect to the database(The following command must be followed by a semicolon '; ') ）3. Use the show statement to

Record some of MySQL's database syntax1 Change root password: mysqladmin-u root password ' 1234561 mysql- u user name-p password go in MySQL monitor1 , show databases; show all database names 2 11, CREATE database;1 CREATE all privileges on test.*

For each webmaster, will encounter the site to test the time. At this time, it is often necessary to back up the database. If you follow the normal operation, the database is exported and backed up locally before being tested on the server. If

sometimes we log in to the database via the MySQL connection command on the Linux server , then run some commands or query SQL, and then press the keyboard up ARROW key to list them. How to view command history is like looking at the Shell command

Mysql index typeIn MySQL, there are four types of indexes: B-Tree index, Hash index, fulltext indexes and RTree indexes 1. B-Tree indexes are the most frequently used index types in MySQL databases, all other storage engines except the Archive