4D v13Sets and named selections |
||||||||||||||||||||||||||||||||
|
4D v13
Sets and named selections
Sets and named selections
In addition to the manipulations explained in the video, you should also note that: In terms of memory:
The table below sums up the all of possibilities for sets and temporary selections:
You can only compare sets from the same table. Warning: The behavior of a set implies during a limited time and eventually using semaphores (see 4D documentation for more information). In fact, a set makes a bit correspond to the physical position of each table record. In case of deleting and then adding records, the former content of a physical record could be replaced by the new content that is no longer in line with what the set is supposed to represent. Be methodical in the use of sets, which remain an efficient and fast way to compare selections. To keep a selection, there’s a third solution that involves using an array that contains your identification using the SELECTION TO ARRAY command. You can use a fourth solution using stored clusters; for example, in BLOBs. Of course, when selections are no longer necessary, you can free up memory by erasing them. CLEAR SET("SetName") |
PROPERTIES
Product: 4D |
||||||||||||||||||||||||||||||