ERP database structures
Database structures are the foundation of any ERP system. They define how data is organized, stored, and related – enabling the single source of truth that ERP promises. This article explains relational databases, tables, keys, indexing, and how these concepts relate to integration, data migration, and reporting.
1. Relational database basics
Most ERP systems are built on relational databases. Data is organized into tables (relations) with rows (records) and columns (attributes). The relational model ensures:
- Data integrity: Rules prevent invalid data.
- No redundancy: Each fact stored once.
- Flexibility: Complex queries across tables.
2. Tables & relationships
ERP databases contain hundreds or thousands of tables. Key relationship types:
- One‑to‑many: One customer → many orders.
- Many‑to‑many: Products ↔ suppliers (via junction table).
- One‑to‑one: Rare, but used for splitting large tables.
3. Primary & foreign keys
Primary key (PK): Unique identifier for each row (e.g., CustomerID).
Foreign key (FK): Column that references a PK in another table (e.g., CustomerID in Orders).
CREATE TABLE Customers (
CustomerID INT PRIMARY KEY,
Name VARCHAR(100)
);
CREATE TABLE Orders (
OrderID INT PRIMARY KEY,
CustomerID INT,
FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID)
);
4. Normalization
Normalization eliminates data redundancy and ensures integrity. Common normal forms in ERP:
- 1NF: Atomic columns (no repeating groups).
- 2NF: No partial dependencies.
- 3NF: No transitive dependencies.
Most ERP databases are in 3NF, but some denormalization is used for performance (e.g., reporting tables).
5. Indexing for performance
Indexes speed up data retrieval. Types:
- B‑tree Default, good for equality and range queries.
- Bitmap For low‑cardinality columns (e.g., status).
- Full‑text For text search.
- Clustered Determines physical order of data.
Indexes speed up reporting but slow down writes – a trade‑off.
6. Common ERP tables
| Module | Tables |
|---|---|
| Finance | GL_Accounts, Journal_Entries, Ledgers, Cost_Centers |
| Sales | Customers, Sales_Orders, Invoices, Shipments |
| Inventory | Products, Warehouses, Stock_Transactions, Reorder_Points |
| Procurement | Suppliers, Purchase_Orders, Receipts |
| HR | Employees, Payroll, Timesheets, Leave_Requests |
7. Database vendors in ERP
| ERP | Supported databases |
|---|---|
| SAP | SAP HANA (primary), Oracle, SQL Server, DB2 |
| Oracle ERP | Oracle Database |
| Microsoft Dynamics | SQL Server, Azure SQL |
| Odoo | PostgreSQL |
| NetSuite | Oracle (hidden from customers) |
8. Future: NewSQL & cloud databases
- Cloud databases: AWS RDS, Azure SQL, Google Cloud SQL – managed, scalable.
- NewSQL: Databases like CockroachDB that combine SQL with horizontal scaling.
- In‑memory databases: SAP HANA, Redis – for real‑time analytics.
- Multi‑model: Some ERPs add document stores (JSON) alongside relational.
Key Takeaways
- ERP uses relational databases with tables, keys, and relationships.
- Primary keys uniquely identify rows; foreign keys link tables.
- Normalization reduces redundancy; indexing improves performance.
- Understanding database structure helps with data migration, reporting, and integration.
- Modern ERPs are moving to cloud and in‑memory databases.
Can I directly query the ERP database? Most vendors discourage direct access – it can bypass business logic and security. Use APIs or reporting tools instead.
What is an ERP schema? A schema is a logical container for database objects (tables, views). Some ERPs use schemas to separate modules.
How often are ERP databases backed up? Depends on criticality – often daily with transaction log backups every few hours.
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