Chapter 19

The SQL Standard

Temporal database support was added to the SQL standard in 2011. This lengthy chapter explains that support in detail and compares and contrasts it with the ideas introduced in previous chapters. It discusses “periods” (SQL’s analog of intervals, represented by explicit from/to pairs); an SQL base table can have at most one application time period (corresponding to valid time) and at most one system time period (corresponding to transaction time). SQL supports analogs of certain of the interval operators discussed in previous chapters; unfortunately, however, it has nothing analogous to PACK and UNPACK. The chapter discusses all of these operators, also database design considerations, queries, and updates in the SQL ...

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