MSAccess Context Primer.md

# Access VBA Project Context Primer

## 1. Data Access Model
The project uses Microsoft Access native DAO as the primary data access layer.
Rules:
- DAO.Recordset and DAO.Database are preferred.
- ADO is used only where explicitly referenced.
- QueryDefs represent named queries; SQL strings represent dynamic queries.
- Bound forms use RecordSource for data binding.
- Unbound forms use manual DAO to populate controls.

## 2. Form Event Model
Access forms have a strict event order:
- Load → Open → Current → Activate
- BeforeUpdate → AfterUpdate are used for validation and saving.
- Dirty state indicates unsaved changes.
- Form_Current triggers when navigating between records.
- Record-level validation occurs in BeforeUpdate.

## 3. Bound Form Behavior
Bound forms automatically:
- Manage record navigation.
- Handle locking and concurrency.
- Commit changes when focus leaves control or DoCmd.RunCommand acCmdSaveRecord.
- Reject updates in BeforeUpdate via Cancel = True.

## 4. Module-Level Structure
Public functions serve as application-level APIs.
Private functions are internal helpers.
Utility modules contain reusable logic such as:
- Date/time helpers
- Error handling
- Validation routines
- Recordset helpers

## 5. Queries
QueryDefs:
- Represent stored queries in Access.
- Often used as templates with parameters or SQL replaced dynamically.

SQL strings:
- Used for dynamic filtering, searching, or temporary operations.

Pass-through queries:
- Forward SQL directly to the backend DB (if present).

## 6. Error Handling Conventions
The project uses structured error handlers of this form:
    On Error GoTo Err_Handler
    ...
    Exit Function/Exit Sub
Err_Handler:
    HandleError Err.Number, Err.Description

## 7. Naming Conventions
(Optional: Add your own naming rules)
- frmSomething = Forms
- rptSomething = Reports
- modSomething = Standard modules
- clsSomething = Classes
- qdf = QueryDef
- rs = Recordset

## 8. General Environment Notes
- This is Access Desktop VBA, not VB6 and not .NET.
- Syntax must follow Access VBA rules.
- The default database engine is Jet/ACE.
- No asynchronous operations; all DAO is synchronous.