---
title: "SQL-317: Retrieve SystemUser via ExtractUsers"
summary: Read operation against SystemUser via NHibernate ORM.
status: draft
owner: SAIF Doc Gen
last_reviewed: 2026-09-24
library: SAIF.Services
reference_type: package
---

# SQL-317: Retrieve SystemUser via ExtractUsers

This statement retrieves a single `SYSTEM_USER` record whose `SYSTEM_USER_ID` matches the username being extracted, used by `UserExtractService.ExtractUsers` to look up an existing system user before processing an extract. The SQL is inferred from the NHibernate LINQ query and the `SystemUserMap` mapping shown below — it is not literal SQL text in the source code.

## Classification

| Field | Value |
| --- | --- |
| **SQL ID** | SQL-317 |
| **Operation type** | Read |
| **Execution method** | ORM (NHibernate LINQ) |
| **Database** | Oracle |
| **Schema** | [unqualified]** |
| **Command type** | N/A (ORM-generated) |
| **Business object** | `SystemUser` |
| **Criteria property** | N/A — ORM |
| **Lifecycle method** | `ExtractUsers` |

## Parameters

| Parameter | Direction | Type | Max length | Description |
| --- | --- | --- | --- | --- |
| `:UserName` | Input | string | N/A | Captured member `userExtract.UserName` (`SystemUserRef.UserName`), compared to the identifier `SystemUser.UserName`, which maps to column `SYSTEM_USER_ID`. |

## Tables

| Table | Access | Columns used |
| --- | --- | --- |
| [SYSTEM_USER](../database-tables.md#system_user) | SELECT | `SYSTEM_USER_ID`, `EMAIL_ADDRESS`, `FIRST_NAME`, `LAST_NAME`, `MIDDLE_NAME`, `POSITION_TITLE`, `PHONE_NUM`, `PHONE_EXTENSION_NUM`, `UPDATE_USER`, `UPDATE_DATE`, `UPDATE_NUM`, `SYSTEM_USER_TYPE_CODE` |

## LINQ statement

Source: `Services/SAIF.Services/SystemUsers/UserExtractService.cs:102`

```csharp
// Services/SAIF.Services/SystemUsers/UserExtractService.cs:101
var systemUser =
    _unitOfWork.GetRepository<SystemUser>()
        .Query()
        .FirstOrDefault(x => x.UserName == userExtract.UserName);
```

## 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
SELECT *
FROM (
  SELECT
    SU.SYSTEM_USER_ID,
    SU.EMAIL_ADDRESS,
    SU.FIRST_NAME,
    SU.LAST_NAME,
    SU.MIDDLE_NAME,
    SU.POSITION_TITLE,
    SU.PHONE_NUM,
    SU.PHONE_EXTENSION_NUM,
    SU.UPDATE_USER,
    SU.UPDATE_DATE,
    SU.UPDATE_NUM,
    SU.SYSTEM_USER_TYPE_CODE
  FROM SYSTEM_USER SU
  WHERE SU.SYSTEM_USER_ID = :UserName
)
WHERE ROWNUM <= 1
```

Translation notes:

- `FirstOrDefault` -> Oracle10 `ROWNUM <= 1` wrapper (dialect `OracleDataClientConfiguration.Oracle10`, resolved via Legends).
- `References(SystemUserType).Column("SYSTEM_USER_TYPE_CODE")` contributes the FK column only; `SYSTEM_USER_TYPE_CODE` table is not joined.

## Operations and processes
- UserExtractService.ExtractUsers — see [Operations and processes](../operations-processes.md)

## Sources
- `Services/SAIF.Services/SystemUsers/UserExtractService.cs (L102)`