mysql version 5.7.22 to version 5.5 is, my.ini vary widely, attach my own simple version 5.7.22 my.ini
# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html
# *** DO NOT EDIT THIS FILE. It's a template which will be copied to the
# *** default location during install, and will be replaced if you
# *** upgrade to a newer version of MySQL.
[client]
port=3306
[mysql]
default-character-set=utf8
[mysqld]
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
# These are commonly set, remove the # and set as required.
port=3306
basedir = "D:/phpStudy/PHPTutorial/MySQL"
datadir = "D:/phpStudy/PHPTutorial/MySQL/data"
# port = .....
# server_id = .....
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES
Copy and paste it, make sure my.ini 5.7 is able to identify, and then initialize the database
mysqld --initialize
Otherwise it will report a bunch of errors when I upgraded with the my.ini 5.5, and then eat a lot of bitterness, next time I will directly copy the installation .
When given: When The innodb_system data file 'ibdata1' must be writable: [ERROR] InnoDB
Solution: Turn off mysql, after deleting ib_logfile0, ib_logfile1 data file folder, and then restart mysql
