MySQL

To operate a table, you must first select a database because the table exists in the database.Select Database Mysql> use school;Database changedAfter selecting the database, we can create tables in this database.Create a table Mysql> create table

Recently, MySQL on Windows 2003 experienced a failure in connecting to the database when it was running normally many times. This problem occurs when it was unable to connect to the database or stop or restart MySQL. Restarting the database also did

Recently, mysql Databases have encountered multiple numeric types, including int, bigint, smallint, and tinyint. The difference between int and smallint is confusing. Today, I searched for the following content on the Internet, and made a

Mysql uses a trigger to synchronize two tablesCurrently, the local test is successful.Assume that two local databases a and B have table1 (id, val) and table2 (id, val) in table)Assume that you want to synchronize data updates in table 1 and table 2.

SQL codeCopy codeThe Code is as follows:/*Navicat MySQL Data TransferSource Server: localSource Server Version: 50022Source Host: localhost: 3306Source Database: testTarget Server Type: MYSQLTarget Server versions: 50022File Encoding: 65001Date: 2012

Change the Data Type of a column[SQL]Alter table visitor MODIFY nam VARCHAR (30 );Append a new column[SQL]Alter table visitor ADD age INT;Alter table visitor ADD age int first;Alter table visitor ADD age int after nam;Change column

The following function implements string processing like an array.I. Use a temporary table as an array Copy codeThe Code is as follows:Create function f_split (@ c varchar (2000), @ split varchar (2 ))Returns @ t table (col varchar (20

Use the following method (navicat is used for mysql management). Set the values of the following parameters and the following statements can be executed on the mysql console.Copy codeThe Code is as follows:Show variables like '% timeout % ';Show

SQLPattern Matching allows you to use"_"Match any single character, while"%"Match any number of characters(Including zero characters). InMySQLMedium,SQLIs case-insensitive by default. The following are some examples. NoteSQLMode, cannot use=Or!

After MySQL is installed, a root user and an anonymous user will be automatically created, which is ignored by many users, this is probably because anonymous users are set to be only available locally by default.However, if MySQL is to be used as a

In linux Linux uses utf8 encoding by default, while windows uses gbk encoding, so the above garbled characters may occur.Solve the Problem of garbled data during mysql Import and ExportThe first thing to do is to determine the encoding format of the

Operating System: Windows 7Mysql version: 5.5.22Www.jb51.netWhen you use the command mysqld -- install servicename -- defaults-file = 'file _ name' to create a mysql service, the systemThe system prompts that the service is successfully created, but

I. Concepts MySQL Cluster uses a series of Disk Data objects to implement Disk tables.Tablespaces: serves as a container for other Disk Data objects.Undo log files: stores the information required for transaction rollback. One or more undo log files

1. Mysql errono 1005: The primary and Foreign keys are not completely consistentCheck the following points:A. Does the field exist?B. Whether the types are consistent (pay attention to the unsigned and powerdesign generation issues)C. Database

Brief Description Character Set and verification rulesCharacter Set is a set of symbols and encoding. A collation is a set of rules used to compare characters in a character set.MySql provides strong support in collation, and mongoel does not find

Start and Stop the mysql service in the windowStart mysql databaseNet start mysqlStop a mysql databaseNet stop mysqlRestart the mysql databaseNet restart mysqlCommand line format: use of basic mysql commands 1. Command Cancellation\ C2. Exit the

Write the code below, and I hope you will criticize and correct it.First, the domain object. The annotation method used here is a new version.User. javaCopy codeThe Code is as follows:Package com. bao. sample. s3h4. domain;Import javax. persistence.

My. ini is in the MySQL directory, So I copied a my. ini file on my colleague's machine for modification and put it in a separate place as a backup. The content is as follows:Copy codeThe Code is as follows:# Uncomment or Add only the keys that you

Copy codeThe Code is as follows:Update dede_addonsoft SET dxylink = REPLACE (dxylink, '.zip ', '.rar') where aid> 45553;Copy codeThe Code is as follows:Update 'table _ name' set field = replace(field,'.rar','.7z '); Table_name: name of the table to

Mysql directly changes the storage path of data files to/etc/my. in cnf, modify the datadir and restart the service. However, I searched for more information from the Internet, most of which were changed to my. in cnf, datadir, sock, and startup