MySQL

Integrity constraints are imposed on fields to meet the expected results of the field. For example, a field contains a default value and cannot be NULL.Directly speaking, if the inserted data does not meet the restrictions, the database management

1. Add the primary key (primary key index)Mysql> alter table 'table _ name' add primary key ('column ')2. add UNIQUE (UNIQUE index)Mysql> alter table 'table _ name' add unique ('Column')3. Add an INDEX (Common INDEX)Mysql> alter table 'table _ name'

You can specify the SQL file initially executed after mysql is started in the configuration file. Its syntax is:In [mysqld] or [server], specify:Init-file = D: \ mysql-5.5.28-winx64 \ abc. SQL, followed by the specific SQL file valuePay attention to

Open Terminal Switch to the root directory[Shell @ localhost ~] # Su-uninstall Mysql5.0 from CentOS before installing Mysql5.5.[Root @ localhost ~] # Yum remove mysqlInstall cmake Download the cmakesource code package cmake-2.8.5.tar.gz[Root @

The following is the sample code. When an exception occurs, the exception information is stored in the log table and the subsequent statements are run.If you have better suggestions, please kindly advise.Example of handling Stored Procedure

This error occurs in the past few days.I still don't know if these values are correct solutions. Post it first.If I haven't updated it for a while, please refer to it later.Out of memory (Needed 16777224 bytes) Error resolutionLook at the

Mysql Master/Slave configuration note: There are four machines in total: A (10.1.10.28), B (10.1.10.29), C (10.1.10.30), and D (10.1.10.31 ).After the configuration result: the A-C is the master and slave, B is the slave of A, D is the slave of C.0)

Locking also reduces the overall time for multi-connection testing, although the maximum wait time for them to wait for locking will increase. For example:Copy codeThe Code is as follows:Connection 1 does 1000 insertsConnections 2, 3, and 4 do 1

The MySQL Manual also provides server-side parameters and parameter value descriptions. Currently, we need to pay attention to the server-side parameters that need to be modified or affect performance, it takes a lot of time to explain its usage and

Later, I was working on WordPress. I didn't know that WordPress was using the InnoDB Data Engine at the beginning, so I built a database in the original database. I didn't find any problems at the beginning, it's okay to import the SQL statement. I

// If no data exists, insert new data$ SQL = "INSERT INTO {$ ecs-> table ('cat _ lang ')} (cat_id, lang_id, cat_name, keywords, cat_desc)VALUES ({$ cat_id}, {$ k}, '{$ val ['cat _ name']}', '{$ val ['keyword']}', '{$ val ['cat _ desc']}')On

1: Enable binlog LoggingModify the mysql configuration file mysql. ini and add it under the [mysqld] node.Copy codeThe Code is as follows:# Log-binLog-bin = E:/log/logbin. log Do not include Chinese characters or spaces in the path. Restart the

Show tables or show tables from database;Explanation: displays the names of all tables in the current database.Show databases;Explanation: displays the names of all databases in MYSQL.Show processlist;Explanation: displays all processes running in

The following code passes the test in MYSQL. MSSQL should be able to run without testing.Copy codeThe Code is as follows:# Create a table as followsCreate temporary table tmp (a int, B int, c int );Insert into tmp VALUES (10,100, 1), (, 2), (, 2 );#

If your configuration file uses a configuration file like a my-innodb-heavy-4G.cnf.Mysql can be started normally, but innodb tables cannot be used.The following output is displayed in the error log:InnoDB: Error: log file./ib_logfile0 is of

Copy codeThe Code is as follows:DELIMITER $USE 'servant _ 591up' $Drop procedure if exists 'SP _ move_data '$Create procedure 'SP _ move_data '()BEGINDECLARE v_exit int default 0;DECLARE v_spid BIGINT;DECLARE v_id BIGINT;DECLARE I INT DEFAULT

At the same time, the online access volume continues to increase. For servers with 1 GB of memory, the server even crashes every day or gets stuck from time to time. This problem has plagued me for using MySQL for more than half a month. scalable

Copy codeThe Code is as follows:DELIMITER $CREATEFUNCTION 't_gir'. 'func _ rand_string '(f_num tinyint unsigned, f_type tinyint unsigned)RETURNS varchar (32)BEGIN-- Translate the number to letter.-- No 1 stands for string only.-- No 2 stands for

Copy codeThe Code is as follows:How can I read 15 records randomly from the database?Order by rand () limit 0, 15How to read all records randomly from the database?Order by rand ()However, I checked the MYSQL official manual. The prompt for RAND ()

How to access MySQL through ODBCMySQL ODBC interface is implemented by installing the MyODBC driver, which is cross-platform. For Linux and other Unix operating systems, install the third-party ODBC standard support platform, such as Iodbc.Simple