Module: ArJdbc::Teradata

Defined in:
lib/arjdbc/teradata/adapter.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.jdbc_connection_class ⇒ Object 



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# File 'lib/arjdbc/teradata/adapter.rb', line 12

def self.jdbc_connection_class
  ::ActiveRecord::ConnectionAdapters::TeradataJdbcConnection
end

Instance Method Details

#adapter_name ⇒ Object 



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# File 'lib/arjdbc/teradata/adapter.rb', line 8

def adapter_name
  'Teradata'
end

#add_limit_offset!(sql, options) ⇒ Object

SQL SERVER CODE STARTS HERE



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# File 'lib/arjdbc/teradata/adapter.rb', line 23

def add_limit_offset!(sql, options)
  if options[:limit]
    order = "ORDER BY #{options[:order] || determine_order_clause(sql)}"
    sql.sub!(/ ORDER BY.*$/i, '')
    replace_limit_offset!(sql, options[:limit], options[:offset], order)
  end
end

#determine_order_clause(sql) ⇒ Object 



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# File 'lib/arjdbc/teradata/adapter.rb', line 63

def determine_order_clause(sql)
  return $1 if sql =~ /ORDER BY (.*)$/
  "1"
  #table_name = get_table_name(sql)
  #"#{table_name}.#{determine_primary_key(table_name)}"
end

#determine_primary_key(table_name) ⇒ Object 



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# File 'lib/arjdbc/teradata/adapter.rb', line 70

def determine_primary_key(table_name)
  primary_key = columns(table_name).detect { |column| column.primary || column.identity }
  return primary_key.name if primary_key
  # Look for an id column.  Return it, without changing case, to cover dbs with a case-sensitive collation.
  columns(table_name).each { |column| return column.name if column.name =~ /^id$/i }
  # Give up and provide something which is going to crash almost certainly
  columns(table_name)[0].name
end

#get_table_name(sql) ⇒ Object 



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# File 'lib/arjdbc/teradata/adapter.rb', line 53

def get_table_name(sql)
  if sql =~ /^\s*insert\s+into\s+([^\(\s,]+)\s*|^\s*update\s+([^\(\s,]+)\s*/i
    $1
  elsif sql =~ /\bfrom\s+([^\(\s,]+)\s*/i
    $1
  else
    nil
  end
end

#modify_types(tp) ⇒ Object 



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# File 'lib/arjdbc/teradata/adapter.rb', line 16

def modify_types(tp)
  tp[:integer][:limit] = nil
  tp
end

#replace_limit_offset!(sql, limit, offset, order) ⇒ Object 



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# File 'lib/arjdbc/teradata/adapter.rb', line 31

def replace_limit_offset!(sql, limit, offset, order)
  if limit
    offset ||= 0
    start_row = offset + 1
    end_row = offset + limit.to_i
    find_select = /\b(SELECT(?:\s+DISTINCT)?)\b(.*)/im
    whole, select, rest_of_query = find_select.match(sql).to_a
    rest_of_query.strip!
    if rest_of_query[0] == "1"
      rest_of_query[0] = "*"
    end
    if rest_of_query.chars.first == "*"
      from_table = get_table_name(rest_of_query)
      rest_of_query = from_table + '.' + rest_of_query
    end
    new_sql = "#{select} t.* FROM (SELECT ROW_NUMBER() OVER(#{order}) AS _row_num, #{rest_of_query}"
    new_sql << ") AS t WHERE t._row_num BETWEEN #{start_row.to_s} AND #{end_row.to_s}"
    sql.replace(new_sql)
  end
  sql
end