Appends LIMIT and OFFSET options to an SQL statement, or some SQL fragment that has the same semantics as LIMIT and OFFSET.
options must be a Hash which contains a :limit option and an :offset option.
This method modifies the sql parameter.
add_limit_offset!('SELECT * FROM suppliers', {:limit => 10, :offset => 50})
generates
SELECT * FROM suppliers LIMIT 10 OFFSET 50
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 217 def add_limit_offset!(sql, options) if limit = options[:limit] sql << " LIMIT #{sanitize_limit(limit)}" end if offset = options[:offset] sql << " OFFSET #{offset.to_i}" end sql end
Register a record with the current transaction so that its after_commit and after_rollback callbacks can be called.
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 189 def add_transaction_record(record) last_batch = @_current_transaction_records.last last_batch << record if last_batch end
Begins the transaction (and turns off auto-committing).
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 195 def begin_db_transaction() end
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 246 def case_sensitive_equality_operator "=" end
Commits the transaction (and turns on auto-committing).
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 198 def commit_db_transaction() end
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 227 def default_sequence_name(table, column) nil end
Executes the delete statement and returns the number of rows affected.
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 53 def delete(sql, name = nil) delete_sql(sql, name) end
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 242 def empty_insert_statement_value "VALUES(DEFAULT)" end
Executes the SQL statement in the context of this connection.
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 38 def execute(sql, name = nil, skip_logging = false) end
Returns the last auto-generated ID from the affected table.
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 43 def insert(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil) insert_sql(sql, name, pk, id_value, sequence_name) end
Inserts the given fixture into the table. Overridden in adapters that require something beyond a simple insert (eg. Oracle).
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 238 def insert_fixture(fixture, table_name) execute "INSERT INTO #{quote_table_name(table_name)} (#{fixture.key_list}) VALUES (#{fixture.value_list})", 'Fixture Insert' end
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 250 def limited_update_conditions(where_sql, quoted_table_name, quoted_primary_key) "WHERE #{quoted_primary_key} IN (SELECT #{quoted_primary_key} FROM #{quoted_table_name} #{where_sql})" end
Checks whether there is currently no transaction active. This is done by querying the database driver, and does not use the transaction house-keeping information recorded by increment_open_transactions and friends.
Returns true if there is no transaction active, false if there is a transaction active, and nil if this information is unknown.
Not all adapters supports transaction state introspection. Currently, only the PostgreSQL adapter supports this.
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 67 def outside_transaction? nil end
Set the sequence to the max value of the table’s column.
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 232 def reset_sequence!(table, column, sequence = nil) # Do nothing by default. Implement for PostgreSQL, Oracle, ... end
Rolls back the transaction (and turns on auto-committing). Must be done if the transaction block raises an exception or returns false.
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 202 def rollback_db_transaction() end
Sanitizes the given LIMIT parameter in order to prevent SQL injection.
The limit may be anything that can evaluate to a string via to_s. It should look like an integer, or a comma-delimited list of integers, or an Arel SQL literal.
Returns Integer and Arel::Nodes::SqlLiteral limits as is. Returns the sanitized limit parameter, either as an integer, or as a string which contains a comma-delimited list of integers.
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 263 def sanitize_limit(limit) if limit.is_a?(Integer) || limit.is_a?(Arel::Nodes::SqlLiteral) limit elsif limit.to_s =~ /,/ Arel.sql limit.to_s.split(',').map{ |i| Integer(i) }.join(',') else Integer(limit) end end
Returns an array of record hashes with the column names as keys and column values as values.
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 6 def select_all(sql, name = nil) select(sql, name) end
Returns a record hash with the column names as keys and column values as values.
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 12 def select_one(sql, name = nil) result = select_all(sql, name) result.first if result end
Returns an array of arrays containing the field values. Order is the same as that returned by columns.
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 33 def select_rows(sql, name = nil) end
Returns a single value from a record
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 18 def select_value(sql, name = nil) if result = select_one(sql, name) result.values.first end 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]
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 26 def select_values(sql, name = nil) result = select_rows(sql, name) result.map { |v| v[0] } end
Runs the given block in a database transaction, and returns the result of the block.
Most databases don’t support true nested transactions. At the time of writing, the only database that supports true nested transactions that we’re aware of, is MS-SQL.
In order to get around this problem, transaction will emulate the effect of nested transactions, by using savepoints: dev.mysql.com/doc/refman/5.0/en/savepoints.html Savepoints are supported by MySQL and PostgreSQL, but not SQLite3.
It is safe to call this method if a database transaction is already open, i.e. if transaction is called within another transaction block. In case of a nested call, transaction will behave as follows:
The block will be run without doing anything. All database statements that happen within the block are effectively appended to the already open database transaction.
However, if :requires_new is set, the block will be wrapped in a database savepoint acting as a sub-transaction.
MySQL doesn’t support DDL transactions. If you perform a DDL operation, then any created savepoints will be automatically released. For example, if you’ve created a savepoint, then you execute a CREATE TABLE statement, then the savepoint that was created will be automatically released.
This means that, on MySQL, you shouldn’t execute DDL operations inside a transaction call that you know might create a savepoint. Otherwise, transaction will raise exceptions when it tries to release the already-automatically-released savepoints:
Model.connection.transaction do # BEGIN Model.connection.transaction(:requires_new => true) do # CREATE SAVEPOINT active_record_1 Model.connection.create_table(...) # active_record_1 now automatically released end # RELEASE SAVEPOINT active_record_1 <--- BOOM! database error! end
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 113 def transaction(options = {}) options.assert_valid_keys :requires_new, :joinable last_transaction_joinable = defined?(@transaction_joinable) ? @transaction_joinable : nil if options.has_key?(:joinable) @transaction_joinable = options[:joinable] else @transaction_joinable = true end requires_new = options[:requires_new] || !last_transaction_joinable transaction_open = false @_current_transaction_records ||= [] begin if block_given? if requires_new || open_transactions == 0 if open_transactions == 0 begin_db_transaction elsif requires_new create_savepoint end increment_open_transactions transaction_open = true @_current_transaction_records.push([]) end yield end rescue Exception => database_transaction_rollback if transaction_open && !outside_transaction? transaction_open = false decrement_open_transactions if open_transactions == 0 rollback_db_transaction rollback_transaction_records(true) else rollback_to_savepoint rollback_transaction_records(false) end end raise unless database_transaction_rollback.is_a?(ActiveRecord::Rollback) end ensure @transaction_joinable = last_transaction_joinable if outside_transaction? @open_transactions = 0 elsif transaction_open decrement_open_transactions begin if open_transactions == 0 commit_db_transaction commit_transaction_records else release_savepoint save_point_records = @_current_transaction_records.pop unless save_point_records.blank? @_current_transaction_records.push([]) if @_current_transaction_records.empty? @_current_transaction_records.last.concat(save_point_records) end end rescue Exception => database_transaction_rollback if open_transactions == 0 rollback_db_transaction rollback_transaction_records(true) else rollback_to_savepoint rollback_transaction_records(false) end raise end end end
Send a commit message to all records after they have been committed.
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 318 def commit_transaction_records #:nodoc records = @_current_transaction_records.flatten @_current_transaction_records.clear unless records.blank? records.uniq.each do |record| begin record.committed! rescue Exception => e record.logger.error(e) if record.respond_to?(:logger) && record.logger end end end end
Executes the delete statement and returns the number of rows affected.
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 292 def delete_sql(sql, name = nil) update_sql(sql, name) end
Returns the last auto-generated ID from the affected table.
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 281 def insert_sql(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil) execute(sql, name) id_value end
Send a rollback message to all records after they have been rolled back. If rollback is false, only rollback records since the last save point.
# File lib/active_record/connection_adapters/abstract/database_statements.rb, line 298 def rollback_transaction_records(rollback) #:nodoc if rollback records = @_current_transaction_records.flatten @_current_transaction_records.clear else records = @_current_transaction_records.pop end unless records.blank? records.uniq.each do |record| begin record.rolledback!(rollback) rescue Exception => e record.logger.error(e) if record.respond_to?(:logger) && record.logger end end end end
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