sec curity

only the usage permission. Further authorization is required using the grant command. You can also use the grant command to create an account directly to see subsequent demos. The following is an explanation of usage in the official MySQL manual. The USAGE privilege specifier stands for "no privileges." It is used at the global level withgrant to modify account attributes such as resource limits or SSL characteristics Witho UT affectingexisting account privileges.--Current demo environment [ema

RR Isolation Demo: mysql> show create TABLE rr_100\g; CREATE TABLE ' rr_100 ' (' id ' bigint ' NOT null default ' 0 ', ' value ' varchar () default NULL, PRIMARY KEY (' id ')); Mysql> SELECT @ @global. tx_isolation, @ @tx_isolation; +-----------------------+-----------------+ | @ @global. tx_isolation | @ @tx_isolation | +-----------------------+-----------------+ | Repeatable-read | Repeatable-read | +-----------------------+-----------------+ 1 row in Set (0.00

processing threads and business processing threads, so our test case also configures the business execution thread pool to examine the scheduling effectiveness of their thread pools. Mina thread pool Set io processor:ioacceptor acceptor = new Niosocketacceptor (Integer.parseint (Iopool)) ; Executor:acceptor.getFilterChain (). AddLast ("ThreadPool", New Executorfilter (Integer.parseint OL)); Netty thread pool Set io worker:new nioworkerpool (Executors.newcachedthreadpool (), Integer.parse

Fuzzy query likeReplace any character with%Where goods_name like ' Nokia% ';Clear a few characters on the underlineUnderline wildcard single character,% wildcard anyExercisesTurn a bunch of 10, 20, and 30 numbers into 10,20,30.Which is to remove single digitsQuery out Select outThe MySQL function is used.Floor returns the largest integer less than xLet a bunch of numbers in addition to 10, then floor is a number, also took the 10 digits, then multiply 10It becomes 10,20,30.That means you can upd

Tags: mysql process function InnoDB featuresTo create a table and insert a data statement:Mysql> CREATE TABLE salary (userid int,salary decimal (9,2));Query OK, 0 rows affected (0.11 sec)Mysql> INSERT into salary values (1,1000), (2,2000), (3,3000), (4,4000), (5,5000), (1,NULL);Query OK, 6 rows affected (0.13 sec)Records:6 duplicates:0 warnings:01.if (value,t,f) function: Above 2000 is considered ' high ' a

-mysql/mysql-proxy-0.8.2-linux-glibc2.3-x86-64bit.tar.gz 192.168.1.11: /opt [root @ serv01 opt] # tar-xvf mysql-proxy-0.8.2-linux-glibc2.3-x86-64bit.tar.gz-C/usr/local/[root @ serv01 opt] # cd/usr/local/[root @ serv01 local] # music mysql-proxy-0.8.2-linux-glibc2.3-x86-64bit/mysql-proxy [root @ serv01 local] # ll mysql-proxy/total 24drwxr-xr-x. 2 7157 wheel 4096 Aug 17 2011 bindrwxr-xr-x. 2 7157 wheel 4096 Aug 17 2011 includedrwxr-xr-x. 4 7157 wheel 4096 Aug 17 2011 libdrwxr-xr-x. 2 7157 wheel 4

The MyISAM storage engine only supports table locks, which is the only supported lock type in MySQL versions. With the increasing requirements of applications on transaction integrity and concurrency, MySQL began to develop a transaction-based storage engine, later, we gradually saw the support for page locks for the bdb storage engine and the InnoDB Storage engine that supports row locks (InnoDB is actually a separate company and has now been acquired by Oracle ). However, MyISAM Table locks ar

[Transferred from: http://space.itpub.net/519536/viewspace-631445] When impdp is used to import a database, if a table already exists, Oracle provides the following four processing methods:A. Ignore (Skip, default Act );B. Add (append) based on the original data );C. Drop the table first, create the table, and insert data (replace );D. truncate first, and then complete data insertion (truncate ). Feel the effects of these methods for your reference. 1. Description of the table_exists_action para

this parameter is used to ensure that data is directly written to the hard disk] Example: dd if=/dev/zero of=testfile bs=1M count=512 conv=fdatasync The result on my VM is as follows: [root@localhost ~]# dd if=/dev/zero of=testfile bs=1M count=512 conv=fdatasync512+0 records in512+0 records out536870912 bytes (537 MB) copied, 19.6677 s, 27.3 MB/s We recommend that you run this command multiple times to get the average value. Before executing the preceding command, we recommend that you use the

MySQL Database Advanced query multi-Table query and join Table query Query all emp_name information in the EMP table. Mysql> select * from EMP where emp_name = 'xiaotian '; The query result is as follows: + -------- + ---------- + --------- + ------------ + --------- + | Emp_id | emp_name | emp_age | emp_sal | emp_bir | emp_sex | + -------- + ---------- + --------- + ------------ + --------- + | 100005 | Xiaotian | 27 | 4000 | 1979-07-10 | male | + -------- + ---------- + -

Memory: memory usage may be the most important factor in system performance. If the system frequently switches pages, the memory is insufficient. "Page Swap" is a unit called "page". It moves code and data blocks of a fixed size from Ram to a disk to release memory space. Although some page switches enable Windows 2000 to use more memory than actually, they are acceptable, but frequent page exchanges will reduce system performance. Reducing page switching significantly increases the system respo

Analysis on the solution of creating and last updating timestamp fields in MySQL, mysql FieldBefore writing this article, clarify my MySQL version. mysql> SELECT VERSION();+------------+| VERSION() |+------------+| 5.5.29-log |+------------+1 row in set (0.00 sec) This is the requirement. One table has a created_at field to create the timestamp of this record, and the other field updated_at record to update the timestamp of this record. Let's try th

... mysql> create database yutest0;Query OK, 1 row affected (0.00 sec)mysql> use yutest0;Database changedmysql> create table t1 (name varchar(10));Query OK, 0 rows affected (0.01 sec)mysql> insert into t1 values('AAA');Query OK, 1 row affected (0.00 sec)mysql> insert into t1 values('aaa');Query OK, 1 row affected (0.01 sec