Use the SINCE operator in SQL to filter records based on time intervals from a specific point. It's particularly useful for temporal queries where you need to examine data changes over time.
The SINCE operator compares timestamps against a reference point. It returns all records modified or created within a specified time period after that reference. This is different from simple date filtering which looks at absolute dates.
For example, to find all customer records changed in the last 30 days:
SELECT * FROM customers WHERE SYSTEM_TIME AS OF PERIOD FOR customer_data SINCE 30 DAY;1. Auditing changes: Track modifications to records over specific time periods
2. Temporal analysis: Compare current state with previous states
3. Data versioning: Retrieve specific versions of data based on when they were valid
Many developers confuse SINCE with BETWEEN or WHERE clauses for date ranges. Unlike those, SINCE doesn't look at record creation dates - it examines when data was valid according to your system's temporal tables.
Another mistake is using SINCE without proper temporal table setup. The operator requires your database to support system-versioned temporal tables, which track historical data automatically.
1. When working with non-temporal databases that don't support system-versioned tables
2. For simple date filtering where you only need records before/after specific dates
3. When you need to analyze trends over multiple time periods simultaneously
| Scenario | Use SINCE? |
|---|---|
| Finding records modified in last week | Yes |
| Getting all orders placed in January | No - use standard date filtering |
| Comparing product prices across quarters | No - use multiple date ranges |
I once needed to audit changes to customer addresses for a compliance check. Using SINCE with a 6-month interval gave me exactly the modified records I needed, while standard date filters would have missed many relevant changes.