transaction interface for database handler

transaction.go

// Transactioner is the transaction interface for database handler
// It should only be applicable to SQL database
type Transactioner interface {
	// Rollback a transaction
	Rollback() error
	// Commit a transaction
	Commit() error
	// TxEnd commits a transaction if no errors, otherwise rollback
	// txFunc is the operations wrapped in a transaction
	TxEnd(txFunc func() error) error
	// TxBegin gets *sql.DB from receiver and return a SqlGdbc, which has a *sql.Tx
	TxBegin() (SqlGdbc, error)
}