在日常数据库管理中，按天统计是一项常见且重要的需求。通过MSSQL的强大功能，我们可以高效地完成每日数据统计与分析。

基础日期统计方法

使用GROUP BY配合日期函数是最直接的统计方式：

SELECT 
    CONVERT(date, CreateTime) as StatDate,
    COUNT(*) as DailyCount
FROM Orders
GROUP BY CONVERT(date, CreateTime)
ORDER BY StatDate DESC;

处理时间区间统计

对于需要统计特定时间段内每日数据的情况：

SELECT 
    CAST(CreateTime AS DATE) as DayDate,
    SUM(SalesAmount) as DailySales
FROM SalesRecords
WHERE CreateTime BETWEEN '2023-01-01' AND '2023-12-31'
GROUP BY CAST(CreateTime AS DATE)
ORDER BY DayDate;

性能优化建议

1. 在统计字段上建立合适的索引
2. 考虑使用持久化计算列存储日期部分
3. 对大表使用分区表技术提高查询效率

高级统计技巧

使用窗口函数进行连续日期统计：

WITH DailyStats AS (
    SELECT 
        CAST(CreateTime AS DATE) as StatDate,
        COUNT(*) as DailyOrders
    FROM Orders
    GROUP BY CAST(CreateTime AS DATE)
)
SELECT 
    StatDate,
    DailyOrders,
    AVG(DailyOrders) OVER (ORDER BY StatDate ROWS 6 PRECEDING) as WeeklyAvg
FROM DailyStats
ORDER BY StatDate;

通过合理的索引设计和查询优化，MSSQL能够高效处理海量数据的每日统计需求，为业务决策提供可靠的数据支持。