Subject Re: creating unique key : usingprimair key and foreign key From Mervyn Bick <invalid@invalid.invalid> Date Wed, 3 Feb 2021 19:59:33 +0200 Newsgroups dbase.getting-started On 2021/02/03 18:57, Akshat Kapoor wrote: > I need some more info before I can give a confirmed suggestion. > Are you using dbf tables or some other backend database system. > > If you are using level 7 dbf tables then you have a field type called > autoincrement. Most of the backend database systems support this in some > way or the other. > > If you use autoincrement then the unique number generation routine is > not required. > > I think you should type > help masterRowset > in your command window and press enter. > > It should guide you how to display rows in child tables that are linked > to the current row in main table. As I understand it Dirk's problem is not in displaying the data but getting the correct primary key in the main table to use as a foreign key in the child table. In a multi-user system one can't guarantee that the last record in the main table is the one you've just saved.  Another user may have saved a record a fraction of a second after you.  SQL RDBMs make provision for a programmer to get the value of the primary key of a record just saved. dBASE doesn't. :-( The solution is not to use an autoinc field but rather use a separate sequence generator.  Primary keys do not need to be in numerical order in a table.  They just need to be unique.  If you want to list records in the order in which they were saved add a timestamp.  Get a value BEFORE saving the new parent record and use that.  There is code in the dUFLP (seqval.cc) to do this. Mervyn.