SELECT
    k,
    b_num,
    isNull(b_num),
    if(b_num = 0, -1, b_num),
    if(isNull(b_num), -1, b_num),
    b_str,
    isNull(b_str),
    empty(b_str),
    if(isNull(b_str), 'Others', b_str),
    if(empty(b_str), 'Others', b_str)
FROM
(
    SELECT
        number AS k,
        toInt8(number) AS a_num,
        toString(number) AS a_str
    FROM system.numbers
    LIMIT 10
)
LEFT JOIN
(
    SELECT
        number AS k,
        toInt8(number) AS b_num,
        toString(number) AS b_str
    FROM system.numbers
    LIMIT 5, 10
) USING (k)
ORDER BY k ASC

┌─k─┬─b_num─┬─isNull(b_num)─┬─if(equals(b_num, 0), -1, b_num)─┬─if(isNull(b_num), -1, b_num)─┬─b_str─┬─isNull(b_str)─┬─empty(b_str)─┬─if(isNull(b_str), 'Others', b_str)─┬─if(empty(b_str), 'Others', b_str)─┐
│ 0 │  ᴺᵁᴸᴸ │             1 │                              -1 │                           -1 │ ᴺᵁᴸᴸ  │             1 │         ᴺᵁᴸᴸ │ Others                             │ Others                            │
│ 1 │  ᴺᵁᴸᴸ │             1 │                              -1 │                           -1 │ ᴺᵁᴸᴸ  │             1 │         ᴺᵁᴸᴸ │ Others                             │ Others                            │
│ 2 │  ᴺᵁᴸᴸ │             1 │                              -1 │                           -1 │ ᴺᵁᴸᴸ  │             1 │         ᴺᵁᴸᴸ │ Others                             │ Others                            │
│ 3 │  ᴺᵁᴸᴸ │             1 │                              -1 │                           -1 │ ᴺᵁᴸᴸ  │             1 │         ᴺᵁᴸᴸ │ Others                             │ Others                            │
│ 4 │  ᴺᵁᴸᴸ │             1 │                              -1 │                           -1 │ ᴺᵁᴸᴸ  │             1 │         ᴺᵁᴸᴸ │ Others                             │ Others                            │
│ 5 │     5 │             0 │                               5 │                            5 │ 5     │             0 │            0 │ 5                                  │ 5                                 │
│ 6 │     6 │             0 │                               6 │                            6 │ 6     │             0 │            0 │ 6                                  │ 6                                 │
│ 7 │     7 │             0 │                               7 │                            7 │ 7     │             0 │            0 │ 7                                  │ 7                                 │
│ 8 │     8 │             0 │                               8 │                            8 │ 8     │             0 │            0 │ 8                                  │ 8                                 │
│ 9 │     9 │             0 │                               9 │                            9 │ 9     │             0 │            0 │ 9                                  │ 9                                 │
└───┴───────┴───────────────┴─────────────────────────────────┴──────────────────────────────┴───────┴───────────────┴──────────────┴────────────────────────────────────┴───────────────────────────────────┘