Comparison or Theta Operators
Abstract
Comparison or theta operators are used for joins and control the declarative statements in the language.
Keywords
Data type conversion
Data type promotion
IS <logical value>
IS [NOT] NORMALIZED
IS [NOT] NULL
Monadic operators
Row comparisons
Theta operators
Dr. Codd introduced the term “theta operators” in his early papers for what a programmer would have called a comparison predicate or operator. The large number of data types in SQL makes doing comparisons a little harder than in other programming languages; we have to do more casting. Values of one data type have to be promoted to values of the other data type before the comparison can be done. The available data types are implementation- ...
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