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module ActiveRecord
module ConnectionAdapters # :nodoc:
module DatabaseStatements
# Returns an array of record hashes with the column names as keys and
# column values as values.
def select_all(sql, name = nil) end
# Returns a record hash with the column names as keys and column values
# as values.
def select_one(sql, name = nil) end
# Returns a single value from a record
def select_value(sql, name = nil)
result = select_one(sql, name)
result.nil? ? nil : result.values.first
end
# Returns an array of the values of the first column in a select:
# select_values("SELECT id FROM companies LIMIT 3") => [1,2,3]
def select_values(sql, name = nil)
result = select_all(sql, name)
result.map{ |v| v.values.first }
end
# Executes the SQL statement in the context of this connection.
# This abstract method raises a NotImplementedError.
def execute(sql, name = nil)
raise NotImplementedError, "execute is an abstract method"
end
# Returns the last auto-generated ID from the affected table.
def insert(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil) end
# Executes the update statement and returns the number of rows affected.
def update(sql, name = nil) end
# Executes the delete statement and returns the number of rows affected.
def delete(sql, name = nil) end
# Wrap a block in a transaction. Returns result of block.
def transaction(start_db_transaction = true)
transaction_open = false
begin
if block_given?
if start_db_transaction
begin_db_transaction
transaction_open = true
end
yield
end
rescue Exception => database_transaction_rollback
if transaction_open
transaction_open = false
rollback_db_transaction
end
raise
end
ensure
commit_db_transaction if transaction_open
end
# Begins the transaction (and turns off auto-committing).
def begin_db_transaction() end
# Commits the transaction (and turns on auto-committing).
def commit_db_transaction() end
# Rolls back the transaction (and turns on auto-committing). Must be
# done if the transaction block raises an exception or returns false.
def rollback_db_transaction() end
# Alias for #add_limit_offset!.
def add_limit!(sql, options)
return unless options
add_limit_offset!(sql, options)
end
# Appends +LIMIT+ and +OFFSET+ options to a SQL statement.
# This method *modifies* the +sql+ parameter.
# ===== Examples
# add_limit_offset!('SELECT * FROM suppliers', {:limit => 10, :offset => 50})
# generates
# SELECT * FROM suppliers LIMIT 10 OFFSET 50
def add_limit_offset!(sql, options)
return if options[:limit].nil?
sql << " LIMIT #{options[:limit]}"
sql << " OFFSET #{options[:offset]}" if options.has_key?(:offset) and !options[:offset].nil?
end
end
end
end
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