update friend set cname=cname+'wang' where id=1.

CONCAT(str1,str2,...)

update friend set cname=CONCAT(cname,'.wang') where id=1

update friend set cname=CONCAT_WS('.',cname,'wang') where id=1,

#tar zxvf libunwind-0.98.6.tar.gz
#cd libunwind-0.98.6
#./configure
#make
#make install

#tar zxvf google-perftools-0.94.1.tar.gz
#cd google*
#./configure
#make
#make install

LD_PRELOAD="/usr/local/lib/libtcmalloc.so"

#service mysql restart

UNIX_TIMESTAMP(gz_ydate)<=$key2

UPDATE table SET 被替换的字段名=被复制的字段名  

UPDATE dede_archives SET senddate=pubdate

UPDATE table set 字段名=REPLACE(字段名,'原字符串','替换的字符串') where 已知的字段名 LIKE '%原字符串%'  

UPDATE pw_members set yz=REPLACE(yz,'1','2') where yz LIKE '%1%'

  
　　Example MySQL config file for medium systems.  
　　# Example MySQL config file for medium systems.  
　　#  
　　# This is for a system with little memory (32M - 64M) where MySQL plays  
　　# an important part, or systems up to 128M where MySQL is used together with  
　　# other programs (such as a web server)  
　　#  
　　# You can copy this file to  
　　# /etc/my.cnf to set global options,  
　　# mysql-data-dir/my.cnf to set server-specific options (in this  
　　# installation this directory is /var/lib/mysql) or  
　　# ~/.my.cnf to set user-specific options.  
　　#  
　　# In this file, you can use all long options that a program supports.  
　　# If you want to know which options a program supports, run the program  
　　# with the "--help" option.  
  
　　# The following options will be passed to all MySQL clients  
　　[client]  
　　#password = your_password  
　　port = 3306  
　　socket = /tmp/mysql.sock  
　　#socket = /var/lib/mysql/mysql.sock  
　　# Here follows entries for some specific programs  
  
　　# The MySQL server  
　　[mysqld]  
　　port = 3306  
　　socket = /tmp/mysql.sock  
　　#socket = /var/lib/mysql/mysql.sock  
　　skip-locking  
　　key_buffer = 128M  
　　max_allowed_packet = 1M  
　　table_cache = 256  
　　sort_buffer_size = 1M  
　　net_buffer_length = 16K  
　　myisam_sort_buffer_size = 1M  
　　max_connections=120  
　　#addnew config  
　　wait_timeout =120  
　　back_log=100  
　　read_buffer_size = 1M  
　　thread_cache=32  
　　skip-innodb  
　　skip-bdb  
　　skip-name-resolve  
　　join_buffer_size=512k  
　　query_cache_size = 32M  
　　interactive_timeout=120  
　　long_query_time=10  
　　log_slow_queries= /usr/local/mysql4/logs/slow_query.log  
　　query_cache_type= 1  
　　# Try number of CPU's*2 for thread_concurrency  
　　thread_concurrency = 4  
  
　　#end new config  
　　# Don't listen on a TCP/IP port at all. This can be a security enhancement,  
　　# if all processes that need to connect to mysqld run on the same host.  
　　# All interaction with mysqld must be made via Unix sockets or named pipes.  
　　# Note that using this option without enabling named pipes on Windows  
　　# (via the "enable-named-pipe" option) will render mysqld useless!  
　　#  
　　#skip-networking  
  
　　# Replication Master Server (default)  
　　# binary logging is required for replication  
　　#log-bin  
  
　　# required unique id between 1 and 2^32 - 1  
　　# defaults to 1 if master-host is not set  
　　# but will not function as a master if omitted  
　　server-id = 1  
  
　　# Replication Slave (comment out master section to use this)  
　　#  
　　# To configure this host as a replication slave, you can choose between  
　　# two methods :  
　　#  
　　# 1) Use the CHANGE MASTER TO command (fully described in our manual) -  
　　# the syntax is:  
　　#  
　　# CHANGE MASTER TO MASTER_HOST=, MASTER_PORT=,  
　　# MASTER_USER=, MASTER_PASSWORD= ;  
　　#  
　　# where you replace , , by quoted strings and  
　　# by the master's port number (3306 by default).  
　　#  
　　# Example:  
　　#  
　　# CHANGE MASTER TO MASTER_HOST='125.564.12.1', MASTER_PORT=3306,  
　　# MASTER_USER='joe', MASTER_PASSWORD='secret';  
　　#  
　　# OR  
# 2) Set the variables below. However, in case you choose this method, then  
　　# start replication for the first time (even unsuccessfully, for example  
　　# if you mistyped the password in master-password and the slave fails to  
　　# connect), the slave will create a master.info file, and any later  
　　# change in this file to the variables' values below will be ignored and  
　　# overridden by the content of the master.info file, unless you shutdown  
　　# the slave server, delete master.info and restart the slaver server.  
　　# For that reason, you may want to leave the lines below untouched  
　　# (commented) and instead use CHANGE MASTER TO (see above)  
　　#  
　　# required unique id between 2 and 2^32 - 1  
　　# (and different from the master)  
　　# defaults to 2 if master-host is set  
　　# but will not function as a slave if omitted  
　　#server-id = 2  
　　#  
　　# The replication master for this slave - required  
　　#master-host =  
　　#  
　　# The username the slave will use for authentication when connecting  
　　# to the master - required  
　　#master-user =  
　　#  
　　# The password the slave will authenticate with when connecting to  
　　# the master - required  
　　#master-password =  
　　#  
　　# The port the master is listening on.  
　　# optional - defaults to 3306  
　　#master-port =  
　　#  
　　# binary logging - not required for slaves, but recommended  
　　#log-bin  
  
　　# Point the following paths to different dedicated disks  
　　#tmpdir = /tmp/  
　　#log-update = /path-to-dedicated-directory/hostname  
  
　　# Uncomment the following if you are using BDB tables  
　　#bdb_cache_size = 4M  
　　#bdb_max_lock = 10000  
  
　　# Uncomment the following if you are using InnoDB tables  
　　#innodb_data_home_dir = /var/lib/mysql/  
　　#innodb_data_file_path = ibdata1:10M:autoextend  
　　#innodb_log_group_home_dir = /var/lib/mysql/  
　　#innodb_log_arch_dir = /var/lib/mysql/  
　　# You can set .._buffer_pool_size up to 50 - 80 %  
　　# of RAM but beware of setting memory usage too high  
　　#innodb_buffer_pool_size = 16M  
　　#innodb_additional_mem_pool_size = 2M  
　　# Set .._log_file_size to 25 % of buffer pool size  
　　#innodb_log_file_size = 5M  
　　#innodb_log_buffer_size = 8M  
　　#innodb_flush_log_at_trx_commit = 1  
　　#innodb_lock_wait_timeout = 50  
  
　　[mysqldump]  
　　quick  
　　max_allowed_packet = 16M  
  
　　[mysql]  
　　no-auto-rehash  
　　# Remove the next comment character if you are not familiar with SQL  
　　#safe-updates  
  
　　[isamchk]  
　　key_buffer = 20M  
　　sort_buffer_size = 20M  
　　read_buffer = 2M  
　　write_buffer = 2M  
  
　　[myisamchk]  
　　key_buffer = 20M  
　　sort_buffer_size = 20M  
　　read_buffer = 2M  
　　write_buffer = 2M  
  
　　[mysqlhotcopy]  
　　interactive-timeout