FAIL_NAME和TOTLA_NAME是您不能对其执行操作的别名。

别的办法了
原样：

SELECT
    COUNT(*) AS TOTLA_COUNT,  
    COUNT(
        CASE
            WHEN ( market_val > 0 AND ABS( loan_amt / market_cal * 100 - ratio ) > 5 ) THEN 1
            ELSE NULL
        END
    ) AS FAIL_COUNT,  
    COUNT( FAIL_COUNT / TOTAL_COUNT * 100 ) AS FAIL_RATE  
FROM
    MY_TABLE

字符串
目标：

SELECT a.TOTLA_COUNT, a.FAIL_COUNT
  , FAIL_COUNT / TOTAL_COUNT * 100 AS FAIL_RATE  
FROM (
  SELECT
      COUNT(*) AS TOTLA_COUNT,  
      COUNT(
          CASE
              WHEN ( market_val > 0 AND ABS( loan_amt / market_cal * 100 - ratio ) > 5 ) THEN 1
              ELSE NULL
          END
      ) AS FAIL_COUNT
  FROM
      MY_TABLE
) a

型