使用Ruby DBI模块

原本的DBI模块的安装教程：

1.安装
首先，我是使用mysql进行测试的，你的机器上需要安装mysql数据库。
然后执行：
gem install mysql

到rubyforge下载ruby-DBI,解压后cd到目录运行如下命令：
ruby setup.rb config --with=dbi,dbd_mysql
ruby setup.rb setup
ruby setup.rb install

完整的setup命令参数参考DBI的doc

2.完整例子
DBI是一类似于ODBC的开发式的统一的数据库编程接口，结构层次上可以分为两层：
1.Database Interface——数据库接口层，与数据库无关，提供与数据库无关的标准接口
2.Database Driver——数据库驱动，与数据库相关

DBI也是很简单易用的，一个完整的使用例子，对于初学者可能有点帮助：

require 'dbi'
begin
  #连接数据库
  dbh=DBI.connect("DBI:Mysql:dbi_test:localhost","root","")
  
  dbh.columns("simple").each do |h|
    p h
  end
  #示范3种事务处理方式
  #手动commit
  dbh["AutoCommit"]=false
  1.upto(10) do |i|
    sql = "insert into simple (name, author) VALUES (?, ?)"
    dbh.do(sql, "Song #{i}", "#{i}")
  end
  dbh.commit
  
  #使用transaction方法
  dbh.transaction do |dbh|
    1.upto(10) do |i|
      sql = "insert into simple (name, author) VALUES (?, ?)"
      dbh.do(sql, "Song #{i}", "#{i}")
    end
  end
  
  #使用SQL语句
  dbh.do("SET AUTOCOMMIT=0")
  dbh.do("BEGIN")
  dbh["AutoCommit"]=false
  dbh.do("UPDATE simple set name='test' where id='1'")
  dbh.do("COMMIT")
  
  #查询
  sth=dbh.execute("select count(id) from simple")
  puts "bookCount:#{sth.fetch[0]}"
  sth.finish
  begin
    sth=dbh.prepare("select * from simple")
    sth.execute
    while row=sth.fetch do
      p row
    end
    sth.finish
  rescue
  end
  
  #上面这段查询可以改写为：
  #dbh.select_all("select * from simple") do |row|
  #   p row
  #end   
  
  
  #使用工具类输出xml格式结果集以及测量查询时间
  sql="select * from simple"
  mesuretime=DBI::Utils::measure do
    sth=dbh.execute(sql)
  end 
  puts "SQL:#{sql}"
  puts "Time:#{mesuretime}"
  rows=sth.fetch_all
  col_names=sth.column_names
  sth.finish
  puts DBI::Utils::XMLFormatter.table(rows)
  
  dbh.do("delete from simple")
rescue  DBI::DatabaseError=>e
  puts "error code:#{e.err}"
  puts "Error message:#{e.errstr}"
ensure
  dbh.disconnect if dbh
end   

出现问题：

但是每次我执行第一步的时候就会出现 config: unknown option --with=dbi,dbd_mysql Try 'ruby setup.rb --help' for detailed usage. 

原因分析：

这是由于dbi版本问题造成的。

因此新版本的安装方式如下：

一般方法是：下载dbi（tar.gz或zip格式），CMD下切换到解压的目录，使用以下命令：

ruby setup.rb config （或ruby setup.rb config --with=dbi,dbd_mysql）

ruby setup.rb setup

ruby setup.rb install

报错：

irb(main):001:0> require 'dbi'
LoadError: no such file to load -- deprecated
        from <internal:lib/rubygems/custom_require>:29:in `require'
        from <internal:lib/rubygems/custom_require>:29:in `require'
        from C:/MyProgramFiles/Ruby192/lib/ruby/site_ruby/1.9.1/dbi.rb:48:in `<t
op (required)>'
        from <internal:lib/rubygems/custom_require>:29:in `require'
        from <internal:lib/rubygems/custom_require>:29:in `require'
        from (irb):1
        from C:/MyProgramFiles/Ruby192/bin/irb:12:in `<main>'
irb(main):002:0>

这个问题比较简单，只要安装一个deprecated包，于是我下载了deprecated-3.0.0.gem，安装之后还是报错。

irb(main):001:0> require 'dbi'
NoMethodError: undefined method `deprecate' for DBI::Date:Class
        from C:/MyProgramFiles/Ruby192/lib/ruby/site_ruby/1.9.1/dbi/utils/date.r
b:57:in `<class:Date>'
        from C:/MyProgramFiles/Ruby192/lib/ruby/site_ruby/1.9.1/dbi/utils/date.r
b:7:in `<module:DBI>'
        from C:/MyProgramFiles/Ruby192/lib/ruby/site_ruby/1.9.1/dbi/utils/date.r
b:1:in `<top (required)>'
        from <internal:lib/rubygems/custom_require>:29:in `require'
        from <internal:lib/rubygems/custom_require>:29:in `require'
        from C:/MyProgramFiles/Ruby192/lib/ruby/site_ruby/1.9.1/dbi/utils.rb:56:
in `<top (required)>'
        from <internal:lib/rubygems/custom_require>:29:in `require'
        from <internal:lib/rubygems/custom_require>:29:in `require'
        from C:/MyProgramFiles/Ruby192/lib/ruby/site_ruby/1.9.1/dbi.rb:50:in `<t
op (required)>'
        from <internal:lib/rubygems/custom_require>:29:in `require'
        from <internal:lib/rubygems/custom_require>:29:in `require'
        from (irb):1
        from C:/MyProgramFiles/Ruby192/bin/irb:12:in `<main>'
irb(main):002:0>

再次Google，居然是deprecated-3.0.0.gem太新了！换成deprecated-2.0.1.gem就可以了。

irb(main):001:0> require 'dbi'  
=> true  
irb(main):002:0> 

这个问题还是比较容易解决的，不过要是出现如下问题就不好解决了：

<internal:lib/rubygems/custom_require>:29:in `require': no such file to load -- parsedate (LoadError)
	from <internal:lib/rubygems/custom_require>:29:in `require'
	from c:/Program Files (x86)/RailsInstaller/Ruby1.9.2/lib/ruby/site_ruby/1.9.1/dbi/sql.rb:9:in `<module:DBI>'
	from c:/Program Files (x86)/RailsInstaller/Ruby1.9.2/lib/ruby/site_ruby/1.9.1/dbi/sql.rb:7:in `<top (required)>'
	from <internal:lib/rubygems/custom_require>:29:in `require'
	from <internal:lib/rubygems/custom_require>:29:in `require'
	from c:/Program Files (x86)/RailsInstaller/Ruby1.9.2/lib/ruby/site_ruby/1.9.1/dbi.rb:37:in `<top (required)>'
	from <internal:lib/rubygems/custom_require>:29:in `require'
	from <internal:lib/rubygems/custom_require>:29:in `require'
	from E:/Program/Eclipse/RubyTest/dbi.rb:1:in `<main>'

经过查询之后，才发现原来parsedate在ruby1.9.2中已经被废除了，现在使用的是date。因此这个版本问题真的是没有办法进行解决啦。我现在正在考虑要不要把ruby降级来解决这个问题。尝试中，后面如果解决了会进行更新。