用OVER实现统计

SELECT
    TJobNumber,
    TClientCode,
    TToChargePounds,
    SUM(TToChargePounds) OVER(PARTITION BY TClientCode) TotalToChargePounds,
    CAST(TToChargePounds*100/SUM(TToChargePounds) OVER(PARTITION BY TClientCode) AS DECIMAL(5,2)) Percentage,
    AVG(TToChargePounds) OVER(PARTITION BY TClientCode) AvgToChargePounds,
    MAX(TToChargePounds) OVER(PARTITION BY TClientCode) MaxToChargePounds,
    MIN(TToChargePounds) OVER(PARTITION BY TClientCode) MinToChargePounds,
    COUNT(TToChargePounds) OVER(PARTITION BY TClientCode) CountToChargePounds
FROM
    TaskTransactions
WHERE
    TClientCode IN ('LM1862','L038')

和GROUP BY的不同之处是可以SELECT没有被GROUP BY的字段。而且如果一条记录需要统计多次，则OVER比GROUP BY快。