1. Computer-implemented system for managing a database system with structured data records, in this system at least two internal databases (db 1 , db 2 ) separate from one another being maintained, which databases are to be managed with structured data records concerning one or more transactions, at least a first, graphical and/or alphanumeric interface for a manual input at least of parts of a structured data record of a transaction into one of the databases being provided, and/or at least a second, graphical and/or alphanumeric interface for an input at least of parts of a structured data record of a transaction via a network into one of the databases (db 1 , db 2 ) being provided, at least a third, bidirectional interface for communication with an external database system (db 3 ) via a data network or a data direct line being provided, in order to communicate at least parts of a structured data record of a transaction between at least one of the internal databases (db 1 , db 2 ) and the external database (db 3 ), inputting of a new data record of a transaction into the first database (db 1 ) initiating inputting of a new corresponding data record of the transaction into the second database (db 2 ), (i) the inputting of the new corresponding data record of the transaction into the second database (db 2 ) only taking place if a confirmation was received from the external database (db 3 ) regarding the successful execution of the transaction, and (ii) in the event of a difference between the new data record in the first database (db 1 ) and a probably corresponding new data record from the external database (db 3 ), a probability being assigned to the probably corresponding new data record from the external database (db 3 ) depending on the degree of difference, and (iii) from further data records from the external database (db 3 ) a data record being extracted that has a higher probability of being the correct corresponding new data record from a large number of data records from the external database (db 3 ) to the data record to be input into the second database (db 2 ).