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Contents
module RR
module ConnectionExtenders
# Provides various MySQL specific functionality required by Rubyrep.
module MysqlExtender
RR::ConnectionExtenders.register :mysql => self
# Returns an ordered list of primary key column names of the given table
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
# 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
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
end
end
end
Version data entries
12 entries across 12 versions & 1 rubygems