MySQL

First, the general steps to optimize the database:(A) Use the show status command to understand the frequency of the various SQL executions.(B) Locating SQL statements that perform less efficiently, in two ways:Post-query location: Slow query

1. "Cause of the incident"Today in the project, found to provide the client interface time is very slow, reached more than 2 seconds, I first time, grabbed the interface, looked at the operation of SQL, found to be 2 SQL slow, accounted for more

The skillful use of regular expressionsSecond, skillfully use RAND () to extract random rowsUsing the random number function of rand (), combined with the ORDER BY clause, the function of randomly extracting some rows is done.Third, using GROUP BY's

MySQL usually can only cache read requests, that is, select, but the generalized query statements are included in the deletion and change, because each delete must first find out, each time the increase also must first check (primary key there is no

Today want to actually do a MySQL manual injection, so found a site such as xxxFirst add an ' error ' after the URL, indicating that this site may contain SQL injection vulnerabilities and can be tested in the next stepThe goal is to see if we can

SQL injection is a common problem: the use of the "or" operator in SQL statements or the "/*" and "#" annotations. The former uses logical operations, or uses the characteristics of MySQL statements.Second, the solution:(A) Preparestatement +

PHP$con[Email protected]mysql_connect(' localhost ', ' root ', ', ' 3306 '); if(!$con){ die(' Connection failed '.Mysql_error()); }Else{ Echo' Connected successfully! ‘; } mysql_query(' Set name UTF8 ',$con); mysql_select_db(' Kun '

Error Scenario:Pop-up Error box when using Navicat to open MySQLError code:ERROR 1045 (28000): Access denied for user ' ODBC ' @ ' localhost ' (using Password:no)ERROR 1045 (28000): Access denied for user ' ODBC ' @ ' localhost ' (using Password:yes)

When using the Mysql-front link on another server:Workaround: After using root login on the MySQL server, execute the following SQL statement:MySQL login command: >mysql-u root-p;Then execute the following command:1. Grant all privileges on * * to '

CREATE database database_name; Delete databases: DROP database database_name; using database: use database_name; View the types of storage engines supported by the system: Show Engines: ALTER TABLE offices rename Offices_new; Modify the data type of

MySQL syntax and related commands1. Each SQL command needs to use a semicolon to complete2. You can write a command into multiple lines3. You can cancel our order by \c4. You can exit the current client by \g, exit, CTRL + C, or quit5. You can query

One, indexes can effectively improve the performance of select operations, while affecting the performance of update, create, and delete operations. Each engine has a limit on the number and length of indexes on the table.Second, the design

Search for Orm2 https://github.com/dresende/node-orm2 on GitHub;Download it in the project folder using NPM install ORM and then write the configuration filevarORM = require ("ORM"); Orm.connect ("Mysql://username:[email

This article describes the construction of the entire PHP development environmentdatabase : MYSQL 5.5.50database software : Navicat 11.1.20 and phpadmin 4.6.5.1 OptionalPHP library : PHP 7.0.13server : Apache 2.4.23integrated development software :

Internal connectionSyntax rules: Select *| Field List from the left table inner join right table on the left table. field = Right table. field;External connection1. Left Outer connection:Syntax rules: The Select *| field list from the left table and

First, download the necessary things1.nginx:http://nginx.org/en/download.html2.php:http://php.net/downloads.php3.mysql: (for the time being)Second, installation and configuration1. Configure PHP:Rename the php.ini-development to php.ini and modify

The escape characters in the MySQL language are basically the same as the various programming languages, as shown in the following table Form Meaning / 0 (NUL) characters \ n Line break

First, GROUP BY clauseGroup by words can group data.Example of a Film data table in MySQL5.5 's Sakila database: Find out the total number of movies for each movie levelMySQL>SELECTCOUNT(* as from film > GROUP byThe results are as follows:As

http://blog.csdn.net/isoleo/article/details/508179761, add line number, B table has no substantive effect, just add line number , (Add a column ) an operationSelect @r:= @r+1 as Row_no, pkgname, coefficient, model_idFrom A,(select @r:=0) bLimit 10;2,

The indexOf-like method LOCATE () and indexoflocate in mysql   LOCATE (substr, str), LOCATE (substr, str, pos) The first syntax returns the position of substr In the first occurrence of the string str. The second syntax returns the position of