- SQL


< > (<search condition>)


, "true", "false" "unknown" .

<search condition> ::=

<boolean term>

| <search condition> OR <boolean term>

<boolean term> ::=

<boolean factor>

| <boolean term> AND <boolean factor>

<boolean factor> ::=

[NOT] <boolean primary>

<boolean primary> ::=

<predicate> | (<search condition>)

  1. < > (<column specification>) <, > (<value expression>), < > (<search condition>), < > (<search condition>), < > (<column specification>) <, > (<value expression>) < > (<set function specification>) <> (<subquery>) < > (<search condition>).

  1. , <> (<predicate>) . , < > (<search condition>) <> (<predicate>).
  2. NOT(true) false, NOT(false) true NOT(unknown) unknown. AND OR :

    Ŀ

    AND true false unknown

    Ĵ

    true true false unknown

    Ĵ

    false false false false

    Ĵ

    unknown unknown false unknown




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