MySQL

The MySQL plug-in storage engine is a component of the MySQL database server. It performs actual data I/O operations on the database and allows and enforces a set of specific features for special application requirements. One of the main advantages

Before performing a table scan, the info () function is called to provide additional information for the optimizer. The information required by the optimizer is not specified by the return value. You need to fill in the specific attributes of the

Mysql queries all information on the current day: The Code is as follows: Select * from test where year (regdate) = year (now () and month (regdate) = month (now () and day (regdate) = day (now ()) This is complicated and easy to write: The Code is

MySQL uses an overhead-based optimizer to determine the optimal solution for processing queries. In many cases, MySQL can calculate the best possible query plan, but in some cases, MySQL does not have enough information about the data and has to

With the popularization of networks, more and more network-based applications are available. Network databases are one of them. One or several servers can provide services to many customers. This method brings a lot of convenience to people, but it

The following script uses the namp scanning tool. Therefore, if the nmap scanning tool is not installed in the system, you must first install the tool. Script functions: First, check whether the mysql port exists normally. If the port does not

The error is as follows: Illegal mix of collations (gbk_chinese_ci, IMPLICIT) And (gbk_bin, IMPLICIT) for operation '= ', SQL State: HY000, Error Code: 1267 Error cause: The database encoding is different from the table creation encoding;

Although the query speed is slow for many reasons, if some optimization is adopted, the query problem can be solved to a certain extent. There are many reasons for slow query speed. The following are common causes: 1. No index or no index is used

During this time, I read about how to restore data through Logs and time points in SQL server. I also read some online examples to see how to restore data through logs. Prerequisites: Change the database fault recovery mode to non-simple mode.

I found some information, and then I used the two functions concat () and left () in MySQL string processing () 1. [CONCAT (str1, str2 ,...) Returns a string from the parameter link. If any parameter is NULL, return NULL. There can be more than

Recent projects mainly archive data and pull the data from one database to another, resulting in a large log file for the new database; or the log files are continuously increased during the use of the database, this reduces database performance and

Assume that our table structure is as follows: The Code is as follows:   Create table example (Example_id int not null,Name VARCHAR (50) not null,Value VARCHAR (50) not null,Other_value VARCHAR (50) NOT NULL) We

Differences and usage between mysql and mysqli Mysql is a non-persistent connection function, while mysqli is a permanent connection function. That is to say Mysql opens a connection process at each link, and mysqli runs mysqli multiple times to

The Code is as follows:$ Dsn = "mysql: host = localhost; dbname = group ";$ Db = new PDO ($ dsn, 'root ','');$ Db-> exec ('set names utf8 '); $ SQL = "select conf_id from 'group' group by conf_id ";// $ Pre = $ db-> prepare ($ SQL );// $ Result_arr

To adapt to the ever-changing technologies, a considerable number of software engineers have gradually switched from desktop software such as Microsoft Access and SQL Server to MySQL. Although MySQL is not a rival to SQL Server, many service

I suddenly received an alarm from MySQL. I crashed from the database and restarted continuously. I opened the error log and found that a table was broken. If the innodb table is damaged, you cannot use repair table or other commands to repair myisam.

If a database error occurs, modify the corresponding code and restart mysql. If you encounter a mysql problem, restart mysql to see if the problem can be solved. 1005: An error occurred while creating the table. 1006: database creation failed 1007:

1. View MySQL database servers and database character sets Show variables like '% char % '; 2. view the character sets supported by currently installed MySQL. Show charset; 3. Set the encoding: Modify my. cnf Vi/etc/my. cnf Add under

We often encounter database backup and restoration in website data maintenance. We generally use the following two methods: 1. Use into outfile and load data infile to import and export backup data The advantage of this method is that the exported

Returns the number of affected rows in the previous statement! Similar to @ ERROR, each statement is reset after execution. If it is used in the future, you need to save the variable to a local variable. Any statement not returned sets this variable