Unique or non-unique table key of an internal table, in which the assignment to the table rows is managed using a table index. The key entries of this index are sorted in ascending order. A sorted key is the primary table key of a sorted table and can be assigned to all internal tables as a secondary table key. Sorting occurs according to the comparison rules for the data types of the key fields. When an internal table is accessed using a sorted key, the response time has a logarithmic relation to the number of table entries, since the table is accessed using a binary search.