Reasons a Magic eDeveloper App Can't be Multi-DBMS

Magic eDeveloper advertises multi-dbms support through “gateways”. You design the app once and simply configure the backend gateway to one of many. However, if the application is designed for ISAM (Btrieve), then getting it to run against a SQL backend has many challenges.

1. Most SQL engines will require a unique key although Btrieve does not so the application tables may need to be adjusted.
   
   
2. Btrieve gateway does not let you assign a primary key – but this is highly desirable for SQL. This will likely cause duplicated tables in the table repository. More maintenance!
   
   
3. Usually, a filename is used for the “Data Source Name” – which includes a file extension. This name is then used as the Table Name in SQL – but the Dot can cause problems in SQL.
   
   
4. Along the same lines – Btrieve doesn’t care about the Column and Index names so an unaware developer may introduce characters that won’t work well under SQL.
   
   
5. SQL Statements for ranges and links may be used – but only if the backend is SQL when being developed. So it is difficult to utilize the feature if targeting both Btrieve and SQL.
   
   

In summary, it is possible to have an application that can target Btrieve and SQL gateways. But there will be duplication in various repositories and extra logic to handle this.

And for an application that has been around a while without a thought for SQL before, the effort to convert and then continue maintenance on will be quite heavy.