ruby-regexes

The below ,removes anything but ascii characters like:

variant_type.gsub!(/[^0-9A-Za-z.\-]/, '')



sql = "INSERT INTO my_table VALUES(#{rows[i].map{|x| x.inspect}.join(', ')})"

vs
sql = "INSERT INTO my_table VALUES(#{ ary.map{ |i| '"%s"' % i }.join(', ') })" 
# => "INSERT INTO my_table VALUES(\"value 1\", \"value 2\", \"value 3\")"

puts sql
# >> INSERT INTO my_table VALUES("value 1", "value 2", "value 3")
'"%s"' % i is a String format that wraps a string in double-quotes.



=============================

 # takes [[4]] and makes it into a 4 "integer"
 result = result.join().to_i
 # takes [[4]] and makes it into a 4 "integer"..
 # array to string , strip th "" , remove th [[]] , converts to integer. 
 recordcount = result.to_s.gsub('"',"").gsub(/[\[\]]/, '').to_i
 
 OR like this ... even better:
 irb(main):001:0> arr = [[4]]
=> [[4]]
irb(main):002:0> arr.flatten
=> [4]
irb(main):003:0> arr.flatten[0]
or 
=> 4
irb(main):004:0> arr.flatten.first
=> 4


============================= 
The map method takes an enumerable object and a block, and runs the block for each element, outputting each returned value from the block (the original object is unchanged unless you use map!):

[1, 2, 3].map { |n| n * n } #=> [1, 4, 9]
Array and Range are enumerable types. map with a block returns an Array.  map! mutates the original array.
============================= 
string = "12345678"

=> [["12"], ["34"], ["56"], ["78"]]
irb(main):042:0> string.scan(/(\d)/)
=> [["1"], ["2"], ["3"], ["4"], ["5"], ["6"], ["7"], ["8"]]
irb(main):043:0> string.scan(/(..)/)
=> [["12"], ["34"], ["56"], ["78"]]
irb(main):045:0> string.scan(/(\d{2})/)
=> [["12"], ["34"], ["56"], ["78"]]
irb(main):046:0> string.scan(/(\d{2})/)
=> [["12"], ["34"], ["56"], ["78"]]