Database Backends hinzugefügt

Database-Backends.md

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+Willkommen im Wiki.# Database Backends
+
+Romexis supports multiple database backends. This Docker project currently treats Microsoft SQL Server as the default backend and Firebird as the parallel backend under development.
+
+---
+
+## Backend Identifiers
+
+| `SERVER_DB` | Backend |
+|---|---|
+| `5` | Microsoft SQL Server |
+| `4` | Firebird |
+
+---
+
+## Initialization Scripts
+
+The initialization entry point is:
+
+```text
+/opt/init-romexis-db.sh
+```
+
+This script routes to:
+
+```text
+/opt/init-romexis-mssql-db.sh
+/opt/init-romexis-firebird-db.sh
+```
+
+---
+
+## Version-Aware Initialization
+
+The backend scripts read:
+
+```text
+/opt/romexis/version
+```
+
+Example:
+
+```text
+6.5.3.444.203
+```
+
+They resolve the target schema marker using the explicit Romexis update order.
+
+Example:
+
+```text
+6.5.3 -> 653
+6.5.2 -> 652
+6.5.1 -> 651
+6.4.x -> 64
+3.8.3 -> 383
+```
+
+The scripts do not rely on plain numeric order because Romexis update markers do not sort naturally.
+
+Example:
+
+```text
+6.0 -> 600
+6.1 -> 610
+6.3 -> 63
+6.4 -> 64
+```
+
+---
+
+## Maximum Schema Version
+
+Use:
+
+```env
+ROMEXIS_DB_MAX_VERSION=653
+```
+
+If the Romexis version is newer than the configured maximum marker, initialization continues only up to the max marker and prints a warning.
+
+---
+
+## Existing Databases
+
+If the database already appears initialized, initialization is skipped.
+
+For MSSQL, this is based on database and user presence.
+
+For Firebird, this is based on the presence of core Romexis tables.
+
+Future upgrade logic can be added by reading the existing database schema marker.