oahdr

### 1. Overview
 The `oahdr` table serves as the **Order Acceptance Header** within the ERP system. It records high-level metadata for sales order acceptances, including customer details, reference purchase orders (PO), amendment tracking, and scheduling dates. It is a central entity for production planning, used to compare customer requirements against actual production and stock (FG/WIP).
 
 ### 2. Column Dictionary
 
 | Column | Type | Nullable | Meaning | Allowed Values | SQL Usage |
 | :--- | :--- | :--- | :--- | :--- | :--- |
 | **index** | integer | No | Internal primary identifier. | Primary Key | Filtering/Ordering |
 | **compcode** | string | No | Unique identifier for the company/branch. | e.g., "DAS", "RF2" | Part of Composite Join Key |
 | **oano** | integer | No | **Order Acceptance Number**. The primary document reference. | | Primary Join Key |
 | **oadate** | datetime | No | Date the order acceptance was created. | | Temporal Reporting |
 | **custcode** | string | No | Unique identifier for the customer. | e.g., "HML(D)", "GILH" | Join to `cust` |
 | **pono** | string | Yes | Customer's Purchase Order number. | | Reference/Filtering |
 | **podate** | datetime | Yes | Date of the customer's Purchase Order. | | Reference |
 | **schdatefrom** | string | Yes | Start date for the delivery schedule. | | Planning |
 | **schdateto** | string | Yes | End date for the delivery schedule. | | Planning |
 | **amendno** | integer | No | Amendment version number. | 0 = Original | Version Tracking |
 | **amenddate** | datetime | Yes | Date the document was last amended. | | Audit/History |
 | **reason** | string | Yes | Narrative for the order acceptance or amendment. | | Notes |
 | **custSchNo** | string | Yes | Customer's internal schedule reference number. | | Reference |
 
 ### 3. Relationships & Join Map
 
 The `oahdr` table is a "Parent" header table in the sales and production workflow. Joins should always include `compcode` to maintain data isolation.
 
 #### Primary Detail Joins (One-to-Many)
 * **oadtl**: Joins on `oano` and `compcode`. This retrieves the specific items and quantities accepted.
 * **oasch**: Joins on `oano` and `compcode`. This retrieves the date-wise delivery schedule for the order.
 * **oadtlamnd**: Joins on `oano` and `compcode`. Used to retrieve historical amendment details for specific items.
 
 #### Master Table Joins (Many-to-One)
 * **cust**: Joins on `custcode` and `compcode`. Used to retrieve customer names, addresses, and group codes.
 
 #### Workflow Joins (Functional)
 * **invhdr**: Joins on `oano` and `compcode`. Used to track actual sales/despatches against the accepted order.
 * **podtl**: Joins on `pono`, `custcode`, and `compcode` (Likely). Used to link the acceptance back to pricing and original PO requirements.
 * **Performainvhdr**: Joins on `oano` and `compcode`. Links the acceptance to proforma invoices generated.
 
 ---