第一种
SELECT 
GSLRID AS "路段名称",
CASE WHEN (GSLVCL = '1' OR GSLVCL = '11') THEN COUNT(GSLREF)  END AS "一型流量",
CASE WHEN (GSLVCL = '1' OR GSLVCL = '11') THEN SUM(TRANAMT)   END AS "一型收入",
CASE WHEN (GSLVCL = '2' OR GSLVCL = '12') THEN COUNT(GSLREF)  END AS "二型流量",
CASE WHEN (GSLVCL = '2' OR GSLVCL = '12') THEN SUM(TRANAMT)   END AS "二型收入",
CASE WHEN (GSLVCL = '3' OR GSLVCL = '13') THEN COUNT(GSLREF)  END AS "三型流量",
CASE WHEN (GSLVCL = '3' OR GSLVCL = '13') THEN SUM(TRANAMT)   END AS "三型收入",
CASE WHEN (GSLVCL = '4' OR GSLVCL = '14') THEN COUNT(GSLREF)  END AS "四型流量",
CASE WHEN (GSLVCL = '4' OR GSLVCL = '14') THEN SUM(TRANAMT)   END AS "四型收入",
CASE WHEN (GSLVCL = '5' OR GSLVCL = '15') THEN COUNT(GSLREF)  END AS "五型流量",
CASE WHEN (GSLVCL = '5' OR GSLVCL = '15') THEN SUM(TRANAMT)   END AS "五型收入"
FROM POSONLTRANRECHIS 
GROUP BY GSLRID;

第二种
SELECT 
GSLRID AS "路段名称",
count(CASE WHEN (GSLVCL = '1' OR GSLVCL = '11') THEN 1  END )AS "一型流量",
sum(CASE WHEN (GSLVCL = '1' OR GSLVCL = '11') THEN TRANAMT   END) AS "一型收入",
count(CASE WHEN (GSLVCL = '2' OR GSLVCL = '12') THEN 1  END )AS "二型流量",
sum(CASE WHEN (GSLVCL = '2' OR GSLVCL = '12') THEN TRANAMT   END) AS "二型收入",
count(CASE WHEN (GSLVCL = '3' OR GSLVCL = '13') THEN 1  END) AS "三型流量",
sum(CASE WHEN (GSLVCL = '3' OR GSLVCL = '13') THEN TRANAMT   END) AS "三型收入",
count(CASE WHEN (GSLVCL = '4' OR GSLVCL = '14') THEN 1  END) AS "四型流量",
sum(CASE WHEN (GSLVCL = '4' OR GSLVCL = '14') THEN TRANAMT   END) AS "四型收入",
count(CASE WHEN (GSLVCL = '5' OR GSLVCL = '15') THEN 1  END) AS "五型流量",
sum(CASE WHEN (GSLVCL = '5' OR GSLVCL = '15') THEN TRANAMT   END) AS "五型收入"
FROM POSONLTRANRECHIS 
GROUP BY GSLRID;
请问第一种和第二种有什么区别？为什么第二种可以 第一种不可以？