MySQL

MySQLThe default"Wait_timeout"Is 8 hours, that is, if a connection is idle for more than 8 hours, Mysql will automatically disconnect the connection. If connections is idle for more than 8 hours, Mysql disconnects it, whileDBCPIt is unknown that the

MySQL databaseThe following problems often occur in stored procedures: 1. garbled storage information, especially by executing SQL scripts to add data. 2. The where clause is used to compare Chinese strings, which is also very common. To solve the

This article introduces the problem caused by an illegal hardware shutdown.MySQL databaseOfData Table Corruption, An instance where the database cannot run normally. The next step is the author's troubleshooting process. Let's take a look at it. The

MySQL databaseHow to ImplementCross-Table updateAndData MergingWhat about it? This article uses an example to introduce how to achieve cross-Table update and data merging. The example is as follows: a lot of resource data must be appended to a table

This article mainly introduces someMySQL databaseOfForeign key constraintNext, let's take a look at it. Foreign key constraints must meet the following conditions: Both parent and child tables are innodb, not temporary tables. In a sub-table, an

WindowsLowerCompile MySQLHow is the database implemented? This article introduces this part. First, let's take a look at its compiling environment. I. Environment preparation: 1. Get the latest MySQL source code: the current version is 5.1.44: http:/

The MySQL Forge project aims to provide a community wiki library for MySQL developers to share information. However, Oracle found that in the past few years, the MySQL Community has fewer and fewer Forge users, but more are being visited by spam.

The basic knowledge of creating, modifying, and deleting mysql Data Tables is also the basic knowledge. The following section describes how to create, modify, and delete tables in MySQL, hope to help you. In fact, many people have forgotten a lot

Mysql database operations include data query, data storage, data update, and data deletion. These are the most basic and commonly used statements in the database. I will introduce them one by one, hope to bring me good luck. SELECT query statement

Case study time: ---------------------------------------------------------------------------------------------------------------------------- 1 PRIMARY Index (NULL) idx_gid 5 (NULL) Using where 2 Index_subquery

By default, mysql does not support remote connection. This is also for security consideration. It is very serious to give your database to others. For security considerations, the root account can only be accessed locally, but the root remote access

In linux, mysql is case-insensitive. If you want mysql to be case-insensitive, you can modify lower_case_table_names in my. ini. On the company's server today, tomcat could not read data from mysql. After checking the tomcat log, it found that the

There are many methods to back up data in mysql. The most common method is mysqldump. Another method is to directly copy the database for backup. Let's take a look at it. 1. mysqldump backup method This seems to be the simplest backup method except

A view is a stored SQL SELECT statement, or a virtual table (in MySQL, the view is used in front of the table ). The data can be data from one or several basic tables (or views. It can also be user-defined data. In fact, the view does not store data.

MySQL versions later than MySQL 4.1 Support INSERT... The on duplicate key update syntax allows you to execute three SQL statements (SELECT, INSERT, UPDATE) and reduce them to one statement.For example, the ipstats table structure is as follows:Copy

The environment is CentOS, 1 GB memory, and Mysql5.5.30.Add the following in/etc/my. cnf:Copy codeThe Code is as follows:Skip-external-lockingSkip-name-resolveMax_connections = 1024Query_cache_size = 16 MSort_buffer_size = 1 MTable_cache = 256Innodb_

I suddenly couldn't open MySQL and reported a 10061 error because I didn't know why. I checked the cause and said it was because the database was connected to a conflict, so I had to reinstall it, in the last step, the start service stopped, the

This SQL statement runs slowly for 4 seconds. SELECT (op. cash_payment + op. pos_payment + op. online_payment + op. charge_card_payment) AS real_payment, op. * FROM db_order. 'order _ payment 'AS op WHERE op. order_payment_id in (SELECT oi.

1. Data in relational databases is stored as tables, so the storage engine can also be called the table type (that is, the type of the storage and operation table ). Query supported storage engines in MySQL: show engines; showengines/g or show

During this period, we have been using hadoop and pig to operate on some data. The new data volume generated every week is more than 1 million. For large volumes of data (more than 10 million), insert and update operations, if the insert operation