MySQL

Create temporary columns in mysqlWhen I write an SQL statement today, the following error occurs: SELECT COUNT (s_dayreport. *) FROM s_dayreport INNER JOIN s _Subuser ON s_dayreport.userId = s_subuser.userId WHERE s_subuser.mgrId = 63 error message:

Mysql uses the stored procedure to achieve the effect similar to split. Foreground: the keywords in the database are separated by ";", and the query result set is sorted in descending order according to the number of keyword frames, and display it

Analyze the combination of the aggregate function and the connected table to see such a relation as MERS MERs (cust_id, cust_name, cust_contact) Orders (order_num, cust_id, order_date) If there is such a search statement: SQL code select cust_name,

Linux Command to restart MYSQL 1. startup method 1. start with service: service mysqld start 2. start with mysqld Script:/etc/inint. d/mysqld start 3. start with safe_mysqld: safe_mysqld & 2. stop 1. start with service: service mysqld stop 2. start

Various Mysql time functions mysql time functions are rich 1. SQL code SECOND (t. file_time) 2. current Time SQL code now () 3. select DATE_SUB (curdate (), INTERVAL 1 DAY) 4. timestamp default mysql timestamp Field weird problem create table

Some problems with mysql installation are as follows:/usr/bin/mysql_secure_installation NOTE: running all parts of this script is recommended for all MySQL servers in production use! Please read each step carefully! In order to log into MySQL to

One of mysql learning explain SQL statements: Query time consumed select version (): View mysql version show profiles: Analyze SQL Performance set profiling = 1: Turn on the profiles function, show profile for query x is disabled by default (x is

MYSQL injection statements are only applicable to the statement type. Order by XXUnion select ..... 1 'Union SELECT 1, CONCAT (user (), 0x3a, database (), 0x3a, version () # The two statements are equivalent. 1 'Union SELECT 1, CONCAT_WS (CHAR (58),

Description of problems caused by mysql version upgrade: 1. java code of the mysql statement in ibatis SELECT d. qid, GROUP_CONCAT (epq. qid) qids FROM table1 d, table2 epq WHERE d. qid = # qid # AND d. pid = epq. pid group by d. checkPid LIMIT 1 2

Mac mysql Chinese CHARACTER garbled problem solution it is best to specify the CHARACTER encoding when creating a database or table: create database db_name default character set utf8 default collate utf8_general_ci; // create table order_list (id

MYSQL sharing: the fastest way to split strings and display them in tables [SQL] USE test; CREATE TABLE test. num (xh int primary key); -- create a Number Auxiliary table SET @ I = 0; INSERT INTO test. num (xh) -- write to the Number Auxiliary table

MySQL 5.0 migration to MariaDB 10.0.2 stored procedure cannot be migratedAlways use MySQL 5.0. After a batch of large data tables have been imported recently, the database has become very slow. The reason is that the performance of the InnoDB engine

Mysql error: Lock wait timeout exceeded 1. Lock wait timeout. This is because the current transaction is waiting for other transactions to release the lock resource. You can find tables and statements that compete for Lock resources, optimize your

The three loops in the MySQL stored procedure have three standard loops: while loop, LOOP, and repeat loop. There is also a non-standard loop method: GOTO, but it is best to use this loop method, it is easy to cause program confusion, here is a good

Mysql data import and export structure and data method 1: mysqldump-ukevin-P3306 -- default-character-set = utf8-p-h10.1.15.123 activity sign_in_user> user. the SQL export result contains the table creation script and data that has been inserted.

The information_schema schema table introduces processlist in mysql. We generally use show (full) processlist to view the current connection and handle various database problems. Now in information_schema mode, the processlist table is added after 5.

Mysql implements master-slave synchronization in mysql to achieve master-slave synchronization: Step 1: install one mysql on each of the two machines (my testing machine system is unbutu, mysql5.5 ), if there is only one machine, the mysql port must

Summary MySQL table creation and query optimization tips the MySQL table creation stage is a very important step. The quality and advantages of the table structure directly affect the subsequent management and maintenance, I will share some

Mysql obtains all table names and field comments of the database. 1. obtains field comments. Java code Select COLUMN_NAME column name. DATA_TYPE field type, COLUMN_COMMENT field comment from INFORMATION_SCHEMA.COLUMNS Where table_name = 'companys' #

About how mysql can improve the query speed when processing data of more than one million data. Recently, due to work needs, I began to pay attention to the Optimization Methods of select query statements for Mysql databases. In actual projects, it