I have a vector layer of almost 13000 lines I need to split depending on one of the field, in the format "DateTime" (YYYY-MM-DDTHH:MM:SSS). In total there is 254 unique values in this field.

It seems that QGIS don't allows splitting up a layer in this format. I have tried creating a new field in the Field calculator, and also the tool Refactor fields with no luck, only getting in return the Date, or NULL in the attribute table. I have thought about the regexp_replace function in the Field Calculator, but I don't know how to arrange it to only give me the numbers as output in the new field.

I don't need to have the date and time in the format YYYY-MM-DDTHH:MM:SSS, but I do need to have at least YYYYMMDDHHMM, preferably in integer format, so I can manage to split up the vector layer.

I am still new to QGIS.