---
title: "SQL-220: Sum LegalBillService paid amount"
summary: Sum LegalBillService.PaidAmount per bill to detect zero-pay letters (executed once per bill in a loop).
status: draft
owner: SAIF Doc Gen
last_reviewed: 2026-09-24
library: SAIF.Services
reference_type: package
---

# SQL-220: Sum LegalBillService paid amount

`BillPaymentService.GenerateCheckTransactionsAsync` sums `PaidAmount` across `LegalBillService` rows for a single bill to decide whether the bill is a zero-pay letter. This statement is issued once per approved bill inside a `foreach` loop (`BillPaymentService.cs:181-185`) — an N+1 pattern, not a single aggregate query across all bills.

## Classification

| Field | Value |
| --- | --- |
| **SQL ID** | SQL-220 |
| **Operation type** | Read |
| **Execution method** | ORM (NHibernate LINQ) |
| **Database** | Oracle |
| **Schema** | [unqualified]** |
| **Command type** | N/A (ORM-generated) |
| **Business object** | `LegalBillService` |
| **Criteria property** | N/A — ORM |
| **Lifecycle method** | `GenerateCheckTransactionsAsync` |

## Parameters

| Parameter | Direction | Type | Max length | Description |
| --- | --- | --- | --- | --- |
| `:billId` | Input | long | N/A | `bill.Id`, the current loop-iteration bill's identifier |

## Tables

| Table | Access | Columns used |
| --- | --- | --- |
| [LEGAL_BILL_SERVICE](../database-tables.md#legal_bill_service) | SELECT | LEGAL_BILL_SEQ_NUM, PAID_AMOUNT (aggregate) |

`LEGAL_BILL` is not joined: `s.LegalBill.Id` is the FK identifier `LEGAL_BILL_SERVICE.LEGAL_BILL_SEQ_NUM`.

## LINQ statement

Source: `Services/SAIF.Services/Legal/Bills/BillPaymentService.cs:185`

```csharp
if (_unitOfWork.GetRepository<BillData.LegalBillService>().Query().Where(s => s.LegalBill.Id == bill.Id).Sum(s => s.PaidAmount) <= 0)
{
    controlStats.IdentifiedZeroPayLetters++;
```

## Sample SQL

> **Inferred SQL:** This SQL was inferred from the LINQ statement above and the NHibernate mappings. It is not concrete SQL from source code; NHibernate generates the executed statement at runtime, so aliases, column order, join syntax, and bind-parameter names may differ.

```sql
-- Inferred from LINQ (NHibernate mapping translation); not concrete SQL
-- Executed once per approved bill inside a foreach loop (N+1 pattern)
SELECT SUM(S.PAID_AMOUNT)
FROM   LEGAL_BILL_SERVICE S
WHERE  S.LEGAL_BILL_SEQ_NUM = :billId
```

Translation notes:
- Executed once per approved bill inside the `foreach` (L181-185), which is an N+1 pattern: one `SELECT SUM(...)` statement per bill, not one query for all bills.
- `<= 0` is compared in C#. If a bill has no service lines, `SUM` returns `NULL`; NHibernate's `Sum` over a non-nullable decimal then throws (or yields 0, depending on version) — flag this for runtime verification.

## Operations and processes
- BillPaymentService.GenerateCheckTransactionsAsync — see [Operations and processes](../operations-processes.md)

## Sources
- `Services/SAIF.Services/Legal/Bills/BillPaymentService.cs (L185)`