在 SQL 中写“动态时间”通常是指根据当前时间动态计算日期范围，而不是写死固定日期。以下是几种常见写法（以 SQL Server / MySQL / PostgreSQL 为例）：

 1. 获取当前时间

-- SQL Server
SELECT GETDATE() AS now-- MySQL
SELECT NOW() AS now-- PostgreSQL
SELECT NOW() AS now

 2. 动态时间范围：过去7天

-- SQL Server
WHERE dTestTime >= DATEADD(DAY, -7, GETDATE())-- MySQL
WHERE dTestTime >= DATE_SUB(NOW(), INTERVAL 7 DAY)-- PostgreSQL
WHERE dTestTime >= NOW() - INTERVAL '7 days'

 3. 动态时间范围：当天8:00到当前时间

-- SQL Server
WHERE dTestTime >= CAST(GETDATE() AS DATE) + '08:00:00'AND dTestTime <= GETDATE()-- MySQL
WHERE dTestTime >= CONCAT(CURDATE(), ' 08:00:00')AND dTestTime <= NOW()-- PostgreSQL
WHERE dTestTime >= DATE_TRUNC('day', NOW()) + INTERVAL '8 hours'AND dTestTime <= NOW()

4. 动态时间范围：本周一到当前时间

-- SQL Server（周一为一周第一天）
WHERE dTestTime >= DATEADD(DAY, 1 - DATEPART(WEEKDAY, GETDATE()), CAST(GETDATE() AS DATE)) + '08:00:00'AND dTestTime <= GETDATE()-- MySQL（周一为一周第一天，取决于@@session_variables）
WHERE dTestTime >= DATE_SUB(CURDATE(), INTERVAL WEEKDAY(CURDATE()) DAY) + INTERVAL 8 HOURAND dTestTime <= NOW()-- PostgreSQL
WHERE dTestTime >= DATE_TRUNC('week', NOW()) + INTERVAL '1 day' + INTERVAL '8 hours'  -- 周一AND dTestTime <= NOW()

 5. 动态时间范围：本月1号8:00到当前时间

-- SQL Server
WHERE dTestTime >= DATEFROMPARTS(YEAR(GETDATE()), MONTH(GETDATE()), 1) + '08:00:00'AND dTestTime <= GETDATE()-- MySQL
WHERE dTestTime >= DATE_FORMAT(CURDATE(), '%Y-%m-01 08:00:00')AND dTestTime <= NOW()-- PostgreSQL
WHERE dTestTime >= DATE_TRUNC('month', NOW()) + INTERVAL '8 hours'AND dTestTime <= NOW()

 6. 动态时间范围：前一周（上周一到上周日）

-- SQL Server
WHERE dTestTime >= DATEADD(DAY, -6 - DATEPART(WEEKDAY, GETDATE()), CAST(GETDATE() AS DATE)) + '08:00:00'AND dTestTime < DATEADD(DAY, 1 - DATEPART(WEEKDAY, GETDATE()), CAST(GETDATE() AS DATE)) + '08:00:00'-- MySQL
WHERE dTestTime >= DATE_SUB(CURDATE(), INTERVAL (WEEKDAY(CURDATE()) + 7) DAY) + INTERVAL 8 HOURAND dTestTime < DATE_SUB(CURDATE(), INTERVAL WEEKDAY(CURDATE()) DAY) + INTERVAL 8 HOUR-- PostgreSQL
WHERE dTestTime >= DATE_TRUNC('week', NOW()) - INTERVAL '6 days' + INTERVAL '8 hours'AND dTestTime < DATE_TRUNC('week', NOW()) + INTERVAL '8 hours'

 7. 动态时间范围：过去N小时（如过去12小时）

-- SQL Server
WHERE dTestTime >= DATEADD(HOUR, -12, GETDATE())-- MySQL
WHERE dTestTime >= DATE_SUB(NOW(), INTERVAL 12 HOUR)-- PostgreSQL
WHERE dTestTime >= NOW() - INTERVAL '12 hours'