
Date's popular critique of SQL's three-valued logic [4, 3] purports to demonstrate that SQL queries can produce erroneous results when nulls are present in the database. I argue that this critique is flawed in that Date misinterprets the meaning of his example query. In fact, SQL returns the correct answer to the query posed; Date, however, believes that he is asking a different question. Although his critique is flawed, I agree with Date's general conclusion: SQL's use of nulls and three-valued logic introduces a startling amount of complexity into seemingly straightforward queries.
| selected citations These citations are derived from selected sources. This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | 7 | |
| popularity This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network. | Average | |
| influence This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | Top 10% | |
| impulse This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network. | Average |
