MySQL

1. parameter file2. log filesError log file Xxx.err file (xxx typically represents host name)Slow query log file 1). Typically, you set a threshold to log SQL statements that exceed the value of the execution time to the slow query logYou need to

1. View the current session isolation levelSELECT @ @tx_isolation;2. View the current isolation level of the systemSELECT @ @global. tx_isolation;3. Set the current session isolation levelSet session transaction Isolatin level repeatable read;4. Set

The field of a table has id,uid,name, where ID is self-increment,CREATE TRIGGER trigger_insert_productAfter INSERT on aFor each ROWBEGINInsert into B (uid,name)Select New.id as db_goods_id,New.uid, New.name;ENDThe above trigger when the Insert event

Update and delete operations The SQL statement is relatively simple, but note that when using update, pay attention to the Weher condition limit, the following statement is to update only the email address of ID 10005, if not with the WHERE

use show processlist to see why: The use of a trigger to constantly delete the log, to ensure that each user's log only 10 removed, the CPU utilization rate from table name view and SQL comparison to isolate the root cause: There is an index in

The optimization of MySQL is very important. The other most commonly used and most need to optimize is limit. MySQL's limit brings great convenience to paging, but when the amount of data is large, limit performance drops sharply.Same as 10

Because of business needs, a batch of MySQL data needs to be imported into hbase, and data is now exported from MySQL to HDFs.Version: Hadoop cdh4.5,hbase-0.9461. Entity classYqbean is my entity class, please modify it according to your needs, the

MySQL connection to the server from the client is not connected to the problem of the company to use MySQL to do a test, began to build a MySQL database in their own local program to connect again, did not encounter a problem connected.This time the

modified via MySQL command line:Mysql> set Character_set_client=utf8;Query OK, 0 rows Affected (0.00 sec)Mysql> set Character_set_connection=utf8;Query OK, 0 rows Affected (0.00 sec)Mysql> set Character_set_database=utf8;Query OK, 0 rows Affected (0.

Select DISTINCT vend_id from Products; Distinct to repeat the value, must be placed in front of the column nameSelect Prod_name from Products LIMIT 5; limiting result limitLimit 4 OFFSET 3 : Take 4 lines starting from line 3, = = Limit 3,4Select

MySQL INSERT statementWhen to use single quotes, when not?1. Create a table firstCREATE TABLE User (Username varchar (255),Age int,Marry Boolean,Birthday Date);Note that there must be no comma before the last parenthesis, otherwise an error "2.

MySQL is a common database, and in order to ensure that the data is not lost, MySQL master and slave become a lot of enterprise choice, the principle involved in the introduction of the following: Slave server through the slave_io_running process

MySQL supports batch mode to run a bunch of SQL statements, and the following example is how MySQL runs SQL statements under Windows batch processing.CREATE TABLE Test (ID int,name varchar (20));INSERT into test values (1, ' Watson ');The

--mysql SQL optimization-------------------2014/07/23case of several order byAt first glance the problem seems a bit complicated, and we start with the simplest case.Use this table to illustrate: (10w rows of data)1. The simplest Order――order by

MySQL inserts the data queried in Table a into Table B. MySQL inserts the data queried in Table a into Table B. If table B exists 1 insert into B select * from; If table B does not exist 1

High Availability of MySQL-keepalivd + mutual Master/SlaveObjective: to configure a keepalived Hot Standby architecture and master-slave ReplicationPlanning:Master1 zlm177 192.168.17.177Master2 zlm188 192.168.17.188Vip 192.168.17.166Environment: Red

Fully uninstall mysql (stop the service, uninstall related programs, delete the registry, and uninstall mysql) 1. Stop MySQL Service 2. uninstall mysql-related programs 3. Delete the Registry (run-> regedit), machine-> system->

Use mysqlbinlog to recover data based on location or time pointUse mysqlbinlog to restore data based on location or time pointMySQL backup generally uses full backup and log backup. For example, a full backup is performed every day and a binary log

Optimized query statements in the MySQL database. Most of the time, the system performance bottleneck for websites built based on php + MySQL is often found in MySQL, and the most frequently used statements in MySQL are query statements. Therefore,

Detailed analysis of mysql explain command The mysql explain command is used to show how mysql uses indexes to process select statements and connect tables. We can use this command to analyze the performance bottleneck of the query or table