How to query PostgreSQL to find the balance of a certain account?

I implemented my requirement in 2 ways:

• Off-ledger
• On-ledger

Also, Sneha Damle from R3 provided the SQL query to find an account's balance in her article (Database View paragraph).

From our recent account library samples, you choose to issue the tokens to the Account directly. https://github.com/corda/samples-kotlin/blob/master/Accounts/worldcupticketbooking/workflows/src/main/kotlin/com/t20worldcup/flows/IssueCashFlow.kt#L42

That said, when you do a query, you just need to specifies the externalID to the AccountID.

For example:

class QuerybyAccount(private val whoAmI:String) : FlowLogic<String>() { override val progressTracker = ProgressTracker() @Suspendable override fun call():String { val myAccount = accountService.accountInfo(whoAmI).single().state.data val criteria = QueryCriteria.VaultQueryCriteria(externalIds = listOf(myAccount.identifier.id)) //Ticket val ticketList = serviceHub.vaultService.queryBy<NonFungibleToken>(criteria = criteria).states val myTicketIDs = ticketList.map { it.state.data.tokenType.tokenIdentifier } val tkList = myTicketIDs.map { val uuid = UUID.fromString(it) val queryCriteria = QueryCriteria.LinearStateQueryCriteria(uuid = listOf(uuid),status = Vault.StateStatus.UNCONSUMED) val stateAndRef = serviceHub.vaultService.queryBy<T20CricketTicketState>(queryCriteria).states[0] val description = stateAndRef.state.data.ticketTeam description } //Assets val asset = serviceHub.vaultService.queryBy(FungibleToken::class.java, criteria).states val myMoney = asset.map { it.state.data.amount.quantity.toString() + " " + it.state.data.tokenType.tokenIdentifier} return "\nI have ticket(s) for $tkList" + "\nI have money of $myMoney" }} 

Full code at: https://github.com/corda/samples-kotlin/tree/master/Accounts/worldcupticketbooking