Split Multiple Columns Into Multiple Columns by Delimiter
In SQLite, you have to do it the hard way with the instr() and  substr() functions:

SELECT before_semicolon,
       substr(rest, 1, pos - 1) AS after_semicolon1,
       substr(rest, pos + 1)    AS after_semicolon2
FROM (SELECT before_semicolon,
             rest,
             instr(rest || ';', ';') AS pos
      FROM (SELECT substr(data1, 1, pos - 1) AS before_semicolon,
                   substr(data1, pos + 1)    AS rest
            FROM (SELECT data1, instr(data1 || ';', ';') AS pos
                  FROM example)));


It might be a better idea to create a user-defined function like Postgres's split_part().