MySQL

In e-commerce, there is often a small inventory and a large number of buyers. In the case of high concurrency, how can we ensure that the number of products will not be bought multiple times. In fact, it is very simple to use the transaction + for

The Federated storage engine accesses data in a table in a remote database, rather than a local table. When creating a Federated table, the server creates a table definition file in the database directory. No other table is created because the

Http://www.fastcloud.cn/zhishi/zhishi387.html I wanted to write an article a long time ago to introduce some of the things that Internet DBAs need to do. However, I am not busy with platform construction. Recently, all modules have begun to take

Database Backup is extremely important. If there is no backup, the system will go crazy in the following situations:UPDATE or DELETE whitout where... Table was DROPPed accidentally... INNODB was upload upt... Entire datacenter loses power... From

Private void btnImport_Click (object sender, EventArgs e) {string filePath = textBox1.Text; string importPwd = txtPwd. text; if (string. isNullOrEmpty (filePath) | string. isNullOrEmpty (importPwd) {MessageBox. show ("Please import the file first,

Description of the EXPLAIN column:Table: displays the data of this row about which tableType: this is an important column that shows the type used by the connection. The connection types from the best to the worst are const, eq_reg, ref, range,

Copy codeThe Code is as follows:Create table shujubiao (Id int primary key auto_increment, specified as I integerName varchar (32) not null, which is an unfixed length. The maximum value is 32 characters and cannot be blank.Password varchar (64) not

The slow log in mysql is a log tool used to record SQL statements that have been executed for a long time (beyond long_query_time seconds. Enable slow log Set in my. cnf [mysqld]  slow_query_log=on  slow_query_log_file=mysql-slow  Restart

The following shows the SQL commands used to operate data tables in mysql in my actual work. If any of these statements is incorrect, please advise: C ++ connects to the mysql header file command g ++ is_in_polygon.cpp-o

I. Prerequisites The principle here is only for MySQL databases. Some of the other databases are similar, and some are still different. I have summarized the General Rules of MySQL and have to take special measures in some special cases. Make good

1. The database name, table name, and field name must be separated by lowercase letters and underlines. A) MySQL has the configuration parameter lower_case_table_names, which cannot be changed dynamically. The default value is 0 in linux. That is,

For example, in table: user field: userid name pw, The useid of the user table is not auto-incrementing. Change userid to auto-increment. Run the following statement to add userid auto-increment by 1 each time. Statement: alter table 'user' change

MySQL compares two datetime-type time intervals, in seconds: SELECTTIME_TO_SEC (TIMEDIFF ('2017-02-09 11:24:46 ', '2017-02-09 10:23:46 ')); First read select timediff ('2017-02-09 11:24:46 ', '2017-02-09 10:23:46 ')01:01:00 SELECT TIME_TO_SEC('01:01:

After installing mysql according to the normal steps, it is found that the default directory of datadir isCopy codeThe Code is as follows: C: \ Documents ents and Settings \ All Users \ Application Data \ MySQL Server 5.1 \ dataOriginally, the C

My MySQL uses the default utf8 encoding, and the database is also configured with utf8 encoding. You can use a program to add Chinese data. If you use SQL statements to add data in cmd, an error message similar to Incorrect string value is returned:

Method 1: use the set password commandCopy codeThe Code is as follows:Mysql-u rootMysql> set password for 'root' @ 'localhost' = PASSWORD ('newpass '); Method 2: Use mysqladminCopy codeThe Code is as follows:Mysqladmin-u root password "newpass" If

Analyze slave database 1062 issues and parse slave database binlog. The error is as follows:[Root @ xxxdb0402 tmp] # mysqlbinlog mysql-bin.004271> 4.logERROR: Error in Log_event: read_log_event (): 'read error', data_len: 438, event_type: 2[Root @

In the Email, I received help from my friend laopan. Laopan:Insert into HudsonResult (JobID, EnvironmentID, FirstSessionID, RerunSessionID, State, Desp, OtherInfo) values(Select ID from Hudson where Stream = 'a7510 _ R52_Integration 'and State = 'N'

Basic knowledge1. mysql compilation and Installation2. How to install and configure the mysql 3rd storage engine3. Features of mainstream mysql storage engines (MyISAM/innodb/MEMORY)4. String encoding knowledge5. MySQL user account management6. Data

How to Create a memory table?Creating a MEMORY table is very simple. You only need to specify ENGINE = MEMORY:Copy codeThe Code is as follows:Create table 'tablename' ('columnname' varchar (256) not nul) ENGINE = memory default charset = latin1