问选择名称where案例值>另一个案例值+2

EN

  SELECT instanceName
    , capacitySizeName
    , desiredCapacitySizeName
    , desiredCapValue
    , capvalue 
  FROM ( 
      SELECT instance_name AS instanceName
      , capacity_size_name AS capacitySizeName
      ,  (CASE capacity_size_name 
            WHEN 'small' THEN 1 
            WHEN 'medium' THEN 2 
            WHEN 'large' THEN 3 
            WHEN 'xlarge' THEN 4
            WHEN 'xxlarge' THEN 5 
            WHEN 'mega' THEN 6 
            WHEN 'ultra' THEN 7 
            WHEN 'giga' THEN 8 
            WHEN 'tera' THEN 9 
            WHEN 'peta' THEN 10 END) AS `capValue`
      , u_desired_capacity_size_name AS desiredCapacitySizeName
      , CASE u_desired_capacity_size_name 
            WHEN 'small' THEN 1 
            WHEN 'medium' THEN 2 
            WHEN 'large' THEN 3 
            WHEN 'xlarge' THEN 4 
            WHEN 'xxlarge' THEN 5 
            WHEN 'mega' THEN 6 
            WHEN 'ultra' THEN 7
            WHEN 'giga' THEN 8 
            WHEN 'tera' THEN 9 
            WHEN 'peta' THEN 10 END AS `desiredCapValue` 
  FROM mysql_view 
  WHERE used_for = 'Production'
  ) A 
  WHERE capvalue < desiredCapValue+2 
  LIMIT 10