Notes

A value table only becomes a check table when a foreign key is defined.If you refer to a domain with a value table in a field , but no foreign key wa defined at field level, there is no check.

2)Database Views : Maintance status defines whether you can only read with the view or whether you can also write with it.If a database view was defined with more than one table, you can only read with this view.

If new fields are included in the table or existing fields are deleted, the view is automatically adjusted to this change.


2)Diff btw : SE54 & SM30

When you create a table maintenance generator the system will automatically create the underlying code. The system generates screens for the user to create or edit the entries. This screen can be accessed from SM30 or SM31 transaction.

SE54 is the developer tool to generate / change the maintenance view, which is a set of function modules and screens.
SM30 is the user / administrator tool to use the maintenance view. It internally calls the generated function modules and screens, but those details are hidden from the user.

3)Foreign keys can only be used in screens.Data records can be written to the table without being checked using an ABAP program.Domain equality is essential.Different data elements can be used, but they must refer to the same domains.The requirement for domain equality is only valid for the check field.For all other foreign key fields, it is sufficient if the data type and the field length are equal.

4)SE14 Database Utility ..The database utility provides an analysis tool with which you can find the cause of the error and the current state of all the tables involved in the conversion.

5)Append structures permit you to append fields to a SAP standart table and structures without having to modify the table definition.
If you copy a table to which an append structure has been appended the fields of the append structure become normal fields of the target table.
Customers create append structures in their namespace.The append structures are thus protected aganist overwriting during an upgrade.
No append structures may be created for pooled and cluster tables.
If a long field occurs in a table, it cannot be extended with append structures.This is because such long fields must always be in the last position of field list.
If you as a customer add a append structure to an SAP table, the fields in this append structure should be in the customer namespace for fields, that is they should begin with YY or ZZ