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Notes on Temporal Tables

Hugo Kornelis wraps up a discussion of temporal tables with miscellany:

Of course, it will be a quite common requirement to query products and their suppliers. When querying the present, you can just access the Suppliers and Products table without the “FOR SYSTEM_TIME” keyword, and the execution plan will unsurprisingly show that a regular join of the two “current” tables is used, with no reference to the history table. Nothing special. We already saw in the earlier parts that querying the present simply ignores the history table; joining does not make that different.

But what if, for instance, we want to show all data as it was valid on June 3 at noon? Well, that is also simple. We already know that we can use FOR SYSTEM_TIME AS OF” to get the rows from a single temporal table as they were at a specific time. We can use that syntax for both tables, to get the data we need:

Read on as Hugo dives into some messy problems. Temporal table queries can expand out in complexity very quickly, as this post shows.

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