MySQL

Database Transaction Processing exclusive lock under www.2cto.com make an experiment to verify the effect of the lock Terminal 1, first enter the transaction status and then run the following statement mysql> begin; Query OK, 0 rows affected (0.00

When querying multiple database Field names, the results are duplicated. How can I query duplicate database results? When using mysql, you sometimes need to query records with unique fields. Although mysql provides the keyword distinct to filter out

In database design, for a specific project, the same table prefix is usually specified for all data tables, for example, WordPress Data Tables start with wp _ and Discuz Data Tables start with dz. This not only facilitates differentiation, but also

Mysql slimming method Note: 1. before performing this operation, stop the Database Service and copy the mqslq5 folder for backup. install the Database Connection Tool navicate on the computer where the database is located; 3. delete useless

How to quickly insert a large amount of data in MySQL these days have tried to use different storage engines to insert a large number of MySQL table data, mainly testing the MyISAM storage engine and InnoDB.The following is an experiment:

In linux, start the MYSQL server and configure the self-starting command/usr/local/mysql/bin/mysqld_safe -- user = mysql & note that the MYSQL installation directory www.2cto.com is configured for self-starting through vi/etc/rc. common local

In CentOS, mysqlhotcopy is used to regularly back up MySQL databases (MyISAM storage engine). mysqlhotcopy and mysqldump are compared: the former is a COPY in the sense of a fast file, and the latter is a collection of SQL statements on the database.

Mysql logon problems occur in Windows. when mysql is logged on, the following ERROR occurs: ERROR 1045: Access denied for user: 'root @ localhost' (Using password: YES) www.2cto.com found some solutions from the Internet and finally got a solution.

Example of a MySql stored procedure: SQL code www.2cto.com CREATE DEFINER = 'root' @ '% 'Procedure 'proc _ calculate_combo_price' (IN 'comboid' VARCHAR (36), OUT 'price' DOUBLE, OUT 'reallyprice' DOUBLE) language SQL not deterministic contains SQL

MySQL Proxy-Core layer (Core) Network Core is built on the basis of socket processing implementation, and the client connection and server connection are associated together. [Connection Life Cycle] connection can be in one of the following four

Mysql is often plagued by garbled characters in character encoding management. The following is a simple example of how mysql manages character encoding. Mysql manages character encoding using three different levels: client (character_set_client):

Mysql Query Optimization-Show command we can view MySQL status and variables through the show command to find the System Bottleneck: mysql> show status -- display status information (Extended show status like 'xxx') Mysql> show variables -- display

MySQL update nesting when we want to retrieve the data d1 in col1 (for example, the current blog access volume) of column id = 5 from table 1 in MySQL, when the table1 attribute p1 is updated to d1 + 1, we may think of using this SQL statement [SQL]

Summary of MySql logical Backup Recovery Method 1. Mysql logical Backup 1. use mysqldump command to generate INSERT statement backup this method is similar to the oracle expdp \ exp tool Syntax: mysqldump [arguments]> file_name. SQL help: [root @ gc

Mysql query data for this week, last week, this month, and last month SELECT name, submittime FROM enterprise where yearweek (date_format (submittime, '% Y-% m-% D') = YEARWEEK (now (); query the SELECT name, submittime FROM enterprise where

MYSQL obtains the auto-increment ID in four ways. select max (id) from tablename 2. the SELECT LAST_INSERT_ID () function LAST_INSERT_ID is irrelevant to table. If data is inserted to table a and then to table B, LAST_INSERT_ID changes. Max (id) is

Mysql's FIND_IN_SET () usage FIND_IN_SET (str, strlist) returns the serial number of str in the strlist of the string set (if any parameter is NULL, NULL is returned. If str is not found, 0 is returned, an exception occurs when parameter 1 contains "

Location of the Code involved in the MySQL main process 1. main () in SQL/mysqld. cc 2. the function for receiving the request is: handle_connetions_sockets (), SQL/mysqld. cc 3. request Processing Portal: handle_one_connection (), SQL/SQL _parse.cc

[Mysql] avoids repeated insert records and obtains the id of the duplicate records. Assume that col1 is unique in the tbl column, that is, unique. To avoid duplicate col1 values inserted, you can use the ignore attribute: [SQL] insert ignore...

Flexible handling of mysql Data Import errors is often used to resolve SQL file import to the database. It may be the restoration of the database from the mysqldump script or the database migration. Such an SQL file usually contains many statements.