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Background documentation Equality Condition Locate the document in the library structure

Equality conditions are search conditions with a comparison predicate.

The following applies to equality conditions:

·        The only operator is the relational operator =.

·        You have one of the following forms:

<column_spec>    =    <extended_value_spec>

<column_spec>    =    <subquery>

An equality condition must be in one of these forms before the Optimizer can use it to determine a search strategy. If the equality condition has another form, the Optimizer attempts to transform it.

The Optimizer transforms expressions in the following forms into conditions without NOT, with the negated operator =:

...NOT (<column_spec> <> <extended_value_spec>)

...NOT (<column_spec> <> <subquery>)

The Optimizer then continues to process the transformed condition.

 

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