Is it possible, just using TSQL, to check if the first two characters of a varchar field are alphabetical?
I need to select from my_table only the rows havi
You don't need to use regex, LIKE is sufficient:
WHERE my_field LIKE '[a-zA-Z][a-zA-Z]%'
Assuming that by "alphabetical" you mean only latin characters, not anything classified as alphabetical in Unicode.
Note - if your collation is case sensitive, it's important to specify the range as [a-zA-Z]. [a-z] may exclude A or Z. [A-Z] may exclude a or z.