# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 141
class_attribute :emulate_booleans

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 175
def initialize(connection, logger, connection_options, config)
  super(connection, logger)
  @connection_options, @config = connection_options, config
  @quoted_column_names, @quoted_table_names = {}, {}

  if self.class.type_cast_config_to_boolean(config.fetch(:prepared_statements) { true })
    @prepared_statements = true
    @visitor = Arel::Visitors::MySQL.new self
  else
    @visitor = unprepared_visitor
  end
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 560
def add_column_position!(sql, options)
  if options[:first]
    sql << " FIRST"
  elsif options[:after]
    sql << " AFTER #{quote_column_name(options[:after])}"
  end
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 318
def begin_db_transaction
  execute "BEGIN"
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 322
def begin_isolated_db_transaction(isolation)
  execute "SET TRANSACTION ISOLATION LEVEL #{transaction_isolation_levels.fetch(isolation)}"
  begin_db_transaction
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 597
def case_insensitive_comparison(table, attribute, column, value)
  if column.case_sensitive?
    super
  else
    table[attribute].eq(value)
  end
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 593
def case_sensitive_modifier(node)
  Arel::Nodes::Bin.new(node)
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 499
def change_column_default(table_name, column_name, default)
  column = column_for(table_name, column_name)
  change_column table_name, column_name, column.sql_type, :default => default
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 504
def change_column_null(table_name, column_name, null, default = nil)
  column = column_for(table_name, column_name)

  unless null || default.nil?
    execute("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote(default)} WHERE #{quote_column_name(column_name)} IS NULL")
  end

  change_column table_name, column_name, column.sql_type, :null => null
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 390
def charset
  show_variable 'character_set_database'
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 395
def collation
  show_variable 'collation_database'
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 369
def create_database(name, options = {})
  if options[:collation]
    execute "CREATE DATABASE `#{name}` DEFAULT CHARACTER SET `#{options[:charset] || 'utf8'}` COLLATE `#{options[:collation]}`"
  else
    execute "CREATE DATABASE `#{name}` DEFAULT CHARACTER SET `#{options[:charset] || 'utf8'}`"
  end
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 385
def current_database
  select_value 'SELECT DATABASE() as db'
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 487
def drop_table(table_name, options = {})
  execute "DROP#{' TEMPORARY' if options[:temporary]} TABLE #{quote_table_name(table_name)}"
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 347
def empty_insert_statement_value
  "VALUES ()"
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 302
def execute(sql, name = nil)
  log(sql, name) { @connection.query(sql) }
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 234
def index_algorithms
  { default: 'ALGORITHM = DEFAULT', copy: 'ALGORITHM = COPY', inplace: 'ALGORITHM = INPLACE' }
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 605
def limited_update_conditions(where_sql, quoted_table_name, quoted_primary_key)
  where_sql
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 230
def native_database_types
  NATIVE_DATABASE_TYPES
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 575
def pk_and_sequence_for(table)
  execute_and_free("SHOW CREATE TABLE #{quote_table_name(table)}", 'SCHEMA') do |result|
    create_table = each_hash(result).first[:"Create Table"]
    if create_table.to_s =~ /PRIMARY KEY\s+(?:USING\s+\w+\s+)?\((.+)\)/
      keys = $1.split(",").map { |key| key.delete('`"') }
      keys.length == 1 ? [keys.first, nil] : nil
    else
      nil
    end
  end
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 588
def primary_key(table)
  pk_and_sequence = pk_and_sequence_for(table)
  pk_and_sequence && pk_and_sequence.first
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 259
def quote(value, column = nil)
  if value.kind_of?(String) && column && column.type == :binary
    s = value.unpack("H*")[0]
    "x'#{s}'"
  elsif value.kind_of?(BigDecimal)
    value.to_s("F")
  else
    super
  end
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 282
def quoted_false
  QUOTED_FALSE
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 278
def quoted_true
  QUOTED_TRUE
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 355
def recreate_database(name, options = {})
  drop_database(name)
  sql = create_database(name, options)
  reconnect!
  sql
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 491
def rename_index(table_name, old_name, new_name)
  if supports_rename_index?
    execute "ALTER TABLE #{quote_table_name(table_name)} RENAME INDEX #{quote_table_name(old_name)} TO #{quote_table_name(new_name)}"
  else
    super
  end
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 482
def rename_table(table_name, new_name)
  execute "RENAME TABLE #{quote_table_name(table_name)} TO #{quote_table_name(new_name)}"
  rename_table_indexes(table_name, new_name)
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 34
def schema_creation
  SchemaCreation.new self
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 569
def show_variable(name)
  variables = select_all("SHOW VARIABLES LIKE '#{name}'", 'SCHEMA')
  variables.first['Value'] unless variables.empty?
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 609
def strict_mode?
  self.class.type_cast_config_to_boolean(@config.fetch(:strict, true))
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 207
def supports_index_sort_order?
  true
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 193
def supports_migrations?
  true
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 197
def supports_primary_key?
  true
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 226
def supports_transaction_isolation?
  version[0] >= 5
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 409
def table_exists?(name)
  return false unless name
  return true if tables(nil, nil, name).any?

  name          = name.to_s
  schema, table = name.split('.', 2)

  unless table # A table was provided without a schema
    table  = schema
    schema = nil
  end

  tables(nil, schema, table).any?
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 211
def type_cast(value, column)
  case value
  when TrueClass
    1
  when FalseClass
    0
  else
    super
  end
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 529
def type_to_sql(type, limit = nil, precision = nil, scale = nil)
  case type.to_s
  when 'binary'
    case limit
    when 0..0xfff;           "varbinary(#{limit})"
    when nil;                "blob"
    when 0x1000..0xffffffff; "blob(#{limit})"
    else raise(ActiveRecordError, "No binary type has character length #{limit}")
    end
  when 'integer'
    case limit
    when 1; 'tinyint'
    when 2; 'smallint'
    when 3; 'mediumint'
    when nil, 4, 11; 'int(11)'  # compatibility with MySQL default
    when 5..8; 'bigint'
    else raise(ActiveRecordError, "No integer type has byte size #{limit}")
    end
  when 'text'
    case limit
    when 0..0xff;               'tinytext'
    when nil, 0x100..0xffff;    'text'
    when 0x10000..0xffffff;     'mediumtext'
    when 0x1000000..0xffffffff; 'longtext'
    else raise(ActiveRecordError, "No text type has character length #{limit}")
    end
  else
    super
  end
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 613
def valid_type?(type)
  !native_database_types[type].nil?
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 666
def add_column_sql(table_name, column_name, type, options = {})
  td = create_table_definition table_name, options[:temporary], options[:options]
  cd = td.new_column_definition(column_name, type, options)
  schema_creation.visit_AddColumn cd
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 630
def add_index_length(option_strings, column_names, options = {})
  if options.is_a?(Hash) && length = options[:length]
    case length
    when Hash
      column_names.each {|name| option_strings[name] += "(#{length[name]})" if length.has_key?(name) && length[name].present?}
    when Fixnum
      column_names.each {|name| option_strings[name] += "(#{length})"}
    end
  end

  return option_strings
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 710
def add_index_sql(table_name, column_name, options = {})
  index_name, index_type, index_columns = add_index_options(table_name, column_name, options)
  "ADD #{index_type} INDEX #{index_name} (#{index_columns})"
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 720
def add_timestamps_sql(table_name, options = {})
  [add_column_sql(table_name, :created_at, :datetime, options), add_column_sql(table_name, :updated_at, :datetime, options)]
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 672
def change_column_sql(table_name, column_name, type, options = {})
  column = column_for(table_name, column_name)

  unless options_include_default?(options)
    options[:default] = column.default
  end

  unless options.has_key?(:null)
    options[:null] = column.null
  end

  options[:name] = column.name
  schema_creation.accept ChangeColumnDefinition.new column, type, options
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 643
def quoted_columns_for_index(column_names, options = {})
  option_strings = Hash[column_names.map {|name| [name, '']}]

  # add index length
  option_strings = add_index_length(option_strings, column_names, options)

  # add index sort order
  option_strings = add_index_sort_order(option_strings, column_names, options)

  column_names.map {|name| quote_column_name(name) + option_strings[name]}
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 702
def remove_column_sql(table_name, column_name, type = nil, options = {})
  "DROP #{quote_column_name(column_name)}"
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 706
def remove_columns_sql(table_name, *column_names)
  column_names.map {|column_name| remove_column_sql(table_name, column_name) }
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 715
def remove_index_sql(table_name, options = {})
  index_name = index_name_for_remove(table_name, options)
  "DROP INDEX #{index_name}"
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 724
def remove_timestamps_sql(table_name)
  [remove_column_sql(table_name, :updated_at), remove_column_sql(table_name, :created_at)]
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 687
def rename_column_sql(table_name, column_name, new_column_name)
  options = { name: new_column_name }

  if column = columns(table_name).find { |c| c.name == column_name.to_s }
    options[:default] = column.default
    options[:null] = column.null
    options[:auto_increment] = (column.extra == "auto_increment")
  else
    raise ActiveRecordError, "No such column: #{table_name}.#{column_name}"
  end

  current_type = select_one("SHOW COLUMNS FROM #{quote_table_name(table_name)} LIKE '#{column_name}'", 'SCHEMA')["Type"]
  schema_creation.accept ChangeColumnDefinition.new column, current_type, options
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 621
def subquery_for(key, select)
  subsubselect = select.clone
  subsubselect.projections = [key]

  subselect = Arel::SelectManager.new(select.engine)
  subselect.project Arel.sql(key.name)
  subselect.from subsubselect.as('__active_record_temp')
end

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 655
def translate_exception(exception, message)
  case error_number(exception)
  when 1062
    RecordNotUnique.new(message, exception)
  when 1452
    InvalidForeignKey.new(message, exception)
  else
    super
  end
end