NewStore creates a new SQLStore.

SQLStore provides all functions to execute SQL queries and transactions It's the real implementation of the Store interface that actually interacts with the database.

TransferMoneyTxnResult is the result of the transfer transaction.

TransferMoneyTxnParams contains the input parameters of the transfer transaction.

Store defines all functions to execute db queries and transactions that must be implemented both by a real database store (like SQLStore) and a mock store for testing.