Ruby connection Mysql-MySql2

We introduced the use of Ruby DBI in the previous chapter. In this chapter, we use Ruby to connect Mysql to more efficient drivers. mysql2 is also recommended to connect to MySql in this way.

Installation mysql2 drive:

geminstallmysql2

You need to use –with-mysql-config configuration mysql_config the path of, such as: –with-mysql-config=/some/random/path/bin/mysql_config .

Connect

The syntax for connecting to the database is as follows:

client=Mysql2::Client.new(:host=>"localhost", :username=>"root")

See http://api.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/MysqlAdapter.html for more parameters.

Query

results=client.query("SELECT * FROM users WHERE group='githubbers'")

Special character escape

escaped=client.escape("gi'thu\\"bbe\\0r's")results=client.query("SELECT
* FROM users WHERE group='#{escaped}'")

Calculate the number returned by the result set:

results.count

Iterative result set:

Results. eachdo | row | # row is hash # key value is database field # value is corresponding
Data putrow ["id"] # row ["id"]. class in MySQL==
Fixnumifrow ["dne"] # If it does not exist, it is nilputsrow ["dne"] end

Example

#!/usr/bin/ruby
-wrequire'mysql2'client=Mysql2::Client.new(:host=>'127.0.0.1',
#main engine:username=>'root',#user name:password=>'123456',
#password:database=>'test',
#database:encoding=>'utf8'#coding)results=client.query("SELECT
VERSION()")results.eachdo\|row\|putsrowend

The output of the above instance is as follows:

{"VERSION()"=>"5.6.21"}

Connection option

Mysql2::Client.new(:host, :username, :password, :port, :database,
:socket='/path/to/mysql.sock',
:flags=REMEMBER_OPTIONS\|LONG_PASSWORD\|LONG_FLAG\|TRANSACTIONS\|
PROTOCOL_41\|SECURE_CONNECTION\|MULTI_STATEMENTS,
:encoding='utf8', :read_timeout=seconds, :write_timeout=seconds,
:connect_timeout=seconds, :reconnect=true/false, :local_infile =
true/false, :secure_auth=true/false, :default_file = '/path/to/my.cfg',
:default_group ='my.cfgsection', :init_command => sql )