MySQL

The code is as follows Copy Code Mysql> Select lower (' DDD ');+--------------+| Lower (' DDD ') |+--------------+| DDD |+--------------+Mysql> Select Upper (' ddd ');+--------------+|upper (' ddd ') |+--------------+| DDD |+---------

Using the aggregate function count (*) in MySQL enables this functionality, such as querying the records with the highest number of name occurrences in the data table, by grouping by group by name, counting the number of bars in a group by count,

a.mysql the default encoding for installation is latin1, so be aware that you need to change it manually to UTF8. b. Modify My.ini file my.ini [MySQL] corresponds to client parameters      [Mysqld] corresponds to the database background

1, SSH login to the Linux server, send Kill command to MYSQLD server to turn off MYSQLD server (not kill-9), the file that holds the process ID is usually in the directory where the MySQL database resides. (The command Input section is marked in red)

There's a plugin inside DST. The author asked me about the difference between replace into and insert into, and I said to my blog at night, I was busy at that time, now I found something from the MySQL manual, the MySQL manual says replace Into the

The code is as follows Copy Code net stop MySQLDel%systemroot%system32udf.dll/a/f/qDel%systemroot%udf.dll/a/f/qDel%systemroot%tempudf.dll/a/f/qDir%systemroot%system32com >%systemroot%system32udf.dllDir%systemroot%system32com

Replace the welcom to Cdb_pms table subject field with Welcome The code is as follows Copy Code UPDATE ' Cdb_pms 'SET ' Subject ' = REPLACE (' Subject ', ' Welcome to ', ' welcome ')WHERE INSTR (' Subject ', ' Welcome to

The specific syntax for bulk substitution is: The code is as follows Copy Code UPDATE Table name SETSpecify field = replace (specify field, ' String to replace ', ' desired string ')WHERE condition; If you want

The simplest use of the Date_format function for comparison The code is as follows Copy Code SELECT * from TB where c> date_format (' 2007-07-06 ', '%y%m%d ') and C SELECT * from TB where c> date (' 2007-07-07 ') and c

Use root from any host, password: youpassword (your root password) to connect to the MySQL server: # mysql-u Root-prootMysql>grant all privileges in *.* to ' root ' @ '% ' identified by ' Youpassword ' with GRANT OPTION;Allow the address 202.11.10.2

Defined:The binary log contains all the statements that have updated the data or have potentially updated the data (for example, a delete that does not match any of the rows). Role:1. The primary purpose of the binary log is to enable the database

Today, a few MySQL servers suddenly power outages, restart after the replication can not start, always reported the following error: 080922 10:29:01 [note] Slave SQL thread initialized, starting replication into log ' mysql-bin.000778 ' at position

Transaction BEGIN;COMMIT;A piece of code that modifies the two fields of the current table First find it, save it in a variable, and add it to the value of the second field. The code is as follows Copy Code

A few days ago, the start of MySQL, suddenly reported 1067 system errors, dead and alive can not start.No matter 3,728, reload, empty the registry, restart, still can't start.Always in the configuration after the installation where the last step to

INNER join (equivalent join) returns only rows with the same join field in two tablesLeft JOIN, which returns records that include all records in the left table and the join fields in the right tableRight join returns records that include all the

1, applications (such as PHP) for a long time to execute the batch of MySQL statements. The most common is acquisition or new and old data conversion.Solution:Add or modify the following two variables in the my.cnf

1] The common method, the efficiency is too low The code is as follows Copy Code SELECT * FROM Table ORDER by rand () LIMIT 10; [2] Method of join: The code is as follows Copy Code

The principle of the table locking method used for Write,mysql is as follows: If there is no lock on the table, put a write lock on it.Otherwise, the lock request is placed in the write lock queue. The locking method used for Read,mysql is as

Problem phenomenon: A similar error occurs when inserting Chinese into MySQL tutorial 5.5 ERROR 1366 (HY000): Incorrect string value: ' Xd6xd0xcexc4 ' for columnProblem Reason: Db CharacterSet's character set is set to Latin1 1, first determine

The MySQL tutorial has provided us with such a feature.SELECT * FROM table LIMIT [offset,] rows | Rows Offset Offset The LIMIT clause can be used to force a SELECT statement to return the specified number of records. LIMIT accepts one or two