mymail sec

I am mainly in the maintenance of the OpenStack cloud platform will involve the operation of MySQL database, here to share with you common simple commands, but also to do a little exercise for themselves.1. Log in to the MySQL database123456Where,-h:the IP address or hostname of the MySQL server, if it is a native login, this option can be omitted;- u: Login user Name- p: login password for logged-in user2. View the database mysql> show databases; +--------------------+| Database |+---

input statement. mysql> show variables like '%log'; +--------------------------------+-------+| Variable_name | Value |+--------------------------------+-------+| back_log | 50 || general_log | OFF || innodb_locks_unsafe_for_binlog | OFF || log | OFF || relay_log | || slow_query_log | OFF || sync_binlog | 0 || sync_relay_log | 0 |+--------------------------------+-------+8 rows in set (0.00

MysqlInnoDB row lock implementation method bitsCN.com Mysql InnoDB row lock implementation method InnoDB row lock is implemented by locking the index items on the index. this is different from Oracle in MySQL, the latter is implemented by locking the corresponding data rows in the data block. The implementation of InnoDB row locks means that InnoDB uses row-level locks only when data is retrieved through Index conditions. otherwise, InnoDB uses table locks! In practical applications, pay special

Source: UML Software Engineering Organization1 Windows Performance Counter analysis Object Counter Analysis Processor %precessor time recommended threshold value 85% Memory Available bytes The recommended threshold value is less than 4MB to add memory;In addition, it is recommended to have at least 10% of physical memory value Pages reads/sec Page reads/

Tags: common operation of 3mysql[Email protected] ~]# mysql-uroot-pzaq12wsx #入库mysql> show databases; #查库ERROR 2006 (HY000): MySQL server has gone awayNo connection. Trying to reconnect ...Connection id:24Current database: * * * NONE * * *+--------------------+| Database |+--------------------+| Information_schema || Discuz || MySQL || Test |+--------------------+4 rows in Set (0.04 sec)mysql> use MySQL #切换库No connection. Trying to reconnect ...Connec

character set, up to 65535/(128*3) = 170 characters.three-TestEnvironment Server Version:5.6.26-74.0-log Percona Servermysql> CREATE TABLE T1(id int not NULL auto_increment primary key,-Name varchar (10)) Engine=innodb default charset=utf8mb4;Query OK, 0 rows affected (0.01 sec)Mysql> CREATE TABLE T2(id int not NULL auto_increment primary key,-Name varchar (10)) Engine=innodb default Charset=utf8;Query OK, 0 rows affected (0.01

14 Insert the Age field type before the field name in the test table tinyint (2)Mysql> CREATE TABLE test (ID int (4) not NULL, name varchar (+) not NULL);Query OK, 0 rows affected (0.36 sec)mysql> desc test;+-------+-------------+------+-----+---------+-------+| Field | Type | Null | Key | Default | Extra |+-------+-------------+------+-----+---------+-------+| ID | Int (4) | NO | | NULL | || name | varchar (16) | NO | | NULL | |+-------+---

Label:MySQL links, viewing databases, working with databases, viewing tables mysql> show databases; +--------------------+ | Database | +--------------------+ | Information_schema | | MySQL | | Performance_schema | | QQ | | Test | +--------------------+ 5 rows in Set (0.06 sec) mysql> use QQ; Database changed mysql> desc QQ; ERROR 1146 (42S02): Table ' qq.qq ' doesn ' t exist mysql> desc Table; Error 1064 (42000): You have a error in your SQL syntax;

Mysql InnoDB row lock implementation method InnoDB row lock is implemented by locking the index items on the index. This is different from Oracle in MySQL, the latter is implemented by locking the corresponding data rows in the data block. The implementation of InnoDB row locks means that InnoDB uses row-level locks only when data is retrieved through index conditions. Otherwise, InnoDB uses table locks! In practical applications, pay special attention to the InnoDB row lock feature. Otherwise,

' varchar (100) default null,'Myid' int (11) default null,Primary key ('id '),Unique key 'uniq _ name' ('name '),KEY 'idex _ myid' ('myid ')) ENGINE = InnoDB default charset = utf81 row in set (0.00 sec)Mysql> begin;Mysql> select * from test_gap_lock where myid> 95 for update;+ ---- + ------------ + ------ +| Id | name | myid |+ ---- + ------------ + ------ +| 1 | jiang | 99 || 2 | hubingmei | 99 || 5 | hubingmei4-| 100 |+ ---- + ------------ + ------

means that when a transaction is accessing data and modifying the data has not been committed to the database, another transaction also accesses the data, then the data is used. Session 1: mysql> select @ global. tx_isolation; + --------------------- + | @ global. tx_isolation | + ----------------------- + | REPEATABLE-READ | + ----------------------- + 1 row in set (0.00 sec) mysql> select @ session. tx_isolation; + --------------------- + | @ sessi

End With; or \g.Your MySQL Connection ID is 3Server version:5.6.40 MySQL Community Server (GPL)Copyright (c), 2018, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of the Oracle Corporation and/or itsAffiliates. Other names trademarks of their respectiveOwners.Type ' help ', ' or ' \h ' for help. Type ' \c ' to clear the current input statement.Mysql>5, set the server side, the client, the result set is UTF-8mysql> SET character_set_client = UTF8;Query OK, 0 r

discarded this parameter. Session 1 First add the myid>95 record to a current readMysql> Show CREATE TABLE Test_gap_lock\g1. Row ***************************Table:test_gap_lockCreate table:create Table ' Test_gap_lock ' (' id ' int (one) is not NULL,' Name ' varchar (+) DEFAULT NULL,' myID ' int (one) DEFAULT NULL,PRIMARY KEY (' id '),UNIQUE KEY ' uniq_name ' (' name '),KEY ' Idex_myid ' (' myID ')) Engine=innodb DEFAULT Charset=utf81 row in Set (0.00 sec