/**
 * 單列非空查詢
 * @return
 */

SELECT addList FROM `user` WHERE addList is not null GROUP BY addList;

如圖獲得資料處理：

@Override
public List<Map<String, Object>> userAddList() {
    
    List<Map<String, Object>> maps = userMapper.userAddList();

    List<Map<String, Object>> mapList = new ArrayList<>();
    List<String> setList = new ArrayList<>();

    for (Map<String, Object> map : maps) {
        Map<String, Object> map1 = new HashMap<>();
        String keyName = (String) map.get("addList");
        if (keyName.contains("||")) {
            String[] split = keyName.split("[||]");
            for (String str : split) {
                Map<String, Object> map2 = new HashMap<>();
                if (str != null && !str.isEmpty() && !setList.contains(str)) {
                    map2.put("addList", str);
                    setList.add(str);
                    mapList.add(map2);
                }
            }
        } else {
            if (!setList.contains(keyName)) {
                map1.put("addList", keyName);
                setList.add(keyName);
                mapList.add(map1);
            }
        }
    }

    return mapList;
}

輸出結果為key-value形式：
[{"addList":"1"},{"addList":"2"},{"addList":"3"},{"addList":"4"},{"addList":"5"}]