text: SELECT * FROM gringotts.wizzard_deposits;
  
  -- 2.Problem
  SELECT MAX(`magic_wand_size`) AS 'longest_magic_wand'
  FROM wizzard_deposits
  GROUP BY 'longest_magic_wand';
  
  -- 3.Problem
  SELECT deposit_group, MAX(`magic_wand_size`) AS 'longest_magic_wand'
  FROM wizzard_deposits
  GROUP BY  `deposit_group`
  ORDER BY longest_magic_wand,deposit_group;
  
  -- 4.Problem
  SELECT deposit_group
  FROM wizzard_deposits
  GROUP BY `deposit_group`
  ORDER BY AVG(`magic_wand_size`) ASC LIMIT 1;
  
  -- 5.Problem
  SELECT deposit_group, SUM(deposit_amount) AS 'total_sum'
  FROM wizzard_deposits
  GROUP BY `deposit_group`
  ORDER BY total_sum;
  
  -- 6.Problem
  SELECT deposit_group, SUM(deposit_amount) AS 'total_sum'
  FROM wizzard_deposits
  WHERE magic_wand_creator = 'Ollivander family'
  GROUP BY `deposit_group`
  ORDER BY deposit_group;
  
  -- 7.Problem
  SELECT deposit_group, SUM(deposit_amount) AS 'total_sum'
  FROM wizzard_deposits
  WHERE magic_wand_creator = 'Ollivander family'
  GROUP BY `deposit_group`
  HAVING total_sum < 150000
  ORDER BY total_sum DESC;
  
  -- 8.Problem
  	SELECT deposit_group, magic_wand_creator, MIN(deposit_charge) AS 'min_deposit_charge'
  	FROM wizzard_deposits
  	GROUP BY `deposit_group`, `magic_wand_creator`
  	ORDER BY `magic_wand_creator`, `deposit_group`;
      
  -- 9.Problem
  SELECT '[0-10]' AS `age_group`, COUNT(id) AS `wizard_count` FROM wizzard_deposits
  WHERE age >= 0 && age <= 10
  GROUP BY `age_group`;
  SELECT '[11-20]' AS `age_group`, COUNT(id) AS `wizard_count` FROM wizzard_deposits
  WHERE age >= 11 && age <= 20
  GROUP BY `age_group`;
  SELECT '[21-30]' AS `age_group`, COUNT(id) AS `wizard_count` FROM wizzard_deposits
  WHERE age >= 21 && age <= 30
  GROUP BY `age_group`;
  SELECT '[31-40]' AS `age_group`, COUNT(id) AS `wizard_count` FROM wizzard_deposits
  WHERE age >= 31 && age <= 40
  GROUP BY `age_group`;
  SELECT '[41-50]' AS `age_group`, COUNT(id) AS `wizard_count` FROM wizzard_deposits
  WHERE age >= 41 && age <= 50
  GROUP BY `age_group`;
  SELECT '[51-60]' AS `age_group`, COUNT(id) AS `wizard_count` FROM wizzard_deposits
  WHERE age >= 51 && age <= 60
  GROUP BY `age_group`;
  SELECT '[61+]' AS `age_group`, COUNT(id) AS `wizard_count` FROM wizzard_deposits
  WHERE age >= 61
  GROUP BY `age_group`;
  
  -- 10.Problem
  SELECT left(first_name,1) AS 'first_letter',
  FROM wizzard_deposits
  WHERE deposit_group = 'Troll Chest'
  GROUP  BY first_letter
  ORDER BY first_letter;
  
  -- 11.Problem
  SELECT deposit_group, is_deposit_expired, AVG(deposit_interest) AS 'average_interest'
  FROM wizzard_deposits
  WHERE deposit_start_date > '1985-01-01'
  GROUP BY deposit_group, is_deposit_expired
  ORDER BY deposit_group DESC, is_deposit_expired;
  
  -- 12.Problem
  SELECT sum(a.deposit_amount - b.deposit_amount) AS 'sum_difference'
  FROM wizzard_deposits AS `a`, wizzard_deposits AS `b`
  WHERE b.id = a.id + 1;