Предполагая, что точка останова ВСЕГДА является первой цифрой, затем
SELECT RTRIM(LEFT(col, PATINDEX('%[0-9]%', col + '0') -1)) as District,
STUFF(col, 1, PATINDEX('%[0-9]%', col + '0') -1, '') as HouseAndFlat
FROM ...
например,
with t(col) as (
select
'ALKOŅU 3-20' union all select
'M.LUBŠNAS 16V-9' union all select
'STIEBRU 6-22' union all select
'ANDREJA UPĪĀA IELA 16-2' union all select
'MISNKAS 4 -115' union all select
'CISKADI,BAZNICAS 4')
SELECT RTRIM(LEFT(col, PATINDEX('%[0-9]%', col + '0') -1)) as District,
STUFF(col, 1, PATINDEX('%[0-9]%', col + '0') -1, '') as HouseAndFlat
FROM t