Supernybörjare-fråga om hantera data med SQL

SELECT FROM_UNIXTIME(weight_date,'%d/%m-%Y') AS second_latest_date  FROM table_content WHERE weight_date = (
  SELECT MAX(weight_date) 
  FROM table_content
)
ORDER BY weight_date DESC LIMIT 1;

SELECT FROM_UNIXTIME(weight_date,'%d/%m-%Y') AS second_latest_date  FROM table_content WHERE weight_date < (
  SELECT MAX(weight_date) 
  FROM table_content
)
ORDER BY weight_date DESC LIMIT 1;

SUM(weight_end_week+weight_start_week) AS total_weight_

IF total_weight_latest_date > totalt_weight_pervious_date THEN "more" AS totalt_weight_comparision