谷歌表中的数组公式

Question

I don't know how to fix this function to make it work. Every time it returns #N/A. In column DI have a surname and in C I have first name

=ArrayFormula(
  IFS(
    ROW(B:B)=1; "Pattern";   
    LEN(B:B)=0; IFERROR(1/0);
    ISDATE(B:B)=True; LOWER( CONCATENATE(CONCATENATE(D:D;"."); LEFT(C:C;1)))
  )
)

Answer 1

try in row 1:

={"Pattern"; ARRAYFORMULA(IF(ISDATE_STRICT(B2:B); LOWER(D2:D&"."&LEFT(C2:C; 1)); ))}