CSS first-letter伪元素适用于chrome，但不适用于firefox(CSS first-letter pseudo element works on chrome, but not on firefox)

 如果你想获得每个连续的范围，你需要一个递归的cte。 
 
 SQL DEMO 
 
WITH cte as (
    SELECT V_Key, B_Key, AssignStart, AssignEnd 
    FROM #temptable t1
    UNION ALL
    SELECT t1.V_Key, t1.B_Key, c.AssignStart, t1.AssignEnd 
    FROM #temptable t1
    JOIN cte c
       ON t1.AssignStart = c.AssignEnd
), create_ranges as (
    SELECT V_key, AssignStart, MAX(AssignEnd) as AssignEnd
    FROM cte
    GROUP BY V_key, AssignStart
)
SELECT C1.*
FROM create_ranges c1
LEFT JOIN create_ranges c2
  ON c1.AssignStart BETWEEN c2.AssignStart  AND C2.AssignEnd
 AND c1.AssignStart <> c2.AssignStart
 AND c1.V_key = c2.V_key
WHERE c2.V_key IS NULL 
ORDER BY c1.V_key 
;
 
 OUTPUT 
 
  

If you want get every consecutive range you need a recursive cte.
 
SQL DEMO
 
WITH cte as (
    SELECT V_Key, B_Key, AssignStart, AssignEnd 
    FROM #temptable t1
    UNION ALL
    SELECT t1.V_Key, t1.B_Key, c.AssignStart, t1.AssignEnd 
    FROM #temptable t1
    JOIN cte c
       ON t1.AssignStart = c.AssignEnd
), create_ranges as (
    SELECT V_key, AssignStart, MAX(AssignEnd) as AssignEnd
    FROM cte
    GROUP BY V_key, AssignStart
)
SELECT C1.*
FROM create_ranges c1
LEFT JOIN create_ranges c2
  ON c1.AssignStart BETWEEN c2.AssignStart  AND C2.AssignEnd
 AND c1.AssignStart <> c2.AssignStart
 AND c1.V_key = c2.V_key
WHERE c2.V_key IS NULL 
ORDER BY c1.V_key 
;
 
OUTPUT