Module: RR::ConnectionExtenders::MysqlExtender

Defined in:
lib/rubyrep/connection_extenders/mysql_extender.rb

Overview

Provides various MySQL specific functionality required by Rubyrep.

Instance Method Summary collapse

Instance Method Details

#primary_key_names(table) ⇒ Object

Returns an ordered list of primary key column names of the given table


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# File 'lib/rubyrep/connection_extenders/mysql_extender.rb', line 10

def primary_key_names(table)
  row = self.select_one(<<-end_sql)
    select table_name from information_schema.tables 
    where table_schema = database() and table_name = '#{table}'
  end_sql
  if row.nil?
    raise "table '#{table}' does not exist"
  end
  
  rows = self.select_all(<<-end_sql)
    select column_name from information_schema.key_column_usage
    where table_schema = database() and table_name = '#{table}' 
    and constraint_name = 'PRIMARY'
    order by ordinal_position
  end_sql

  columns = rows.map {|_row| _row['column_name']}
  columns
end

#referenced_tables(tables) ⇒ Object

Returns for each given table, which other tables it references via foreign key constraints.

  • tables: an array of table names

Returns: a hash with

  • key: name of the referencing table

  • value: an array of names of referenced tables


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# File 'lib/rubyrep/connection_extenders/mysql_extender.rb', line 36

def referenced_tables(tables)
  rows = self.select_all(<<-end_sql)
    select distinct table_name as referencing_table, referenced_table_name as referenced_table
    from information_schema.key_column_usage
    where table_schema = database()
    and table_name in ('#{tables.join("', '")}')
  end_sql
  result = {}
  rows.each do |row|
    unless result.include? row['referencing_table']
      result[row['referencing_table']] = []
    end
    if row['referenced_table'] != nil
      result[row['referencing_table']] << row['referenced_table']
    end
  end
  tables.each do |table|
    result[table] = [] unless result.include? table
  end
  result
end