[Koha] SQL report

Hi! How do I find only four digits at the beginning of a string? Example, there are values. 1234 2345 123456 25-1 24-11 VK-2 -123 123* At the exit, I need to get 1234 2345 regexp '^[0-9]{4}' does not give the desired result. My test: SELECT itemnumber, biblionumber, barcode, stocknumber, withdrawn, itemnotes_nonpublic, itype FROM items WHERE stocknumber regexp '^[0-9]{4}' AND itype = "BK" Good Luck! Igor A. Sychev Tomsk Polytechnic University https://lib.tpu.ru