4D v19
exists_predicate
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- Syntax rules
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- arithmetic_expression
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- column_definition
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- comparison_predicate
- exists_predicate
- foreign_key_definition
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4D v19
exists_predicate
exists_predicate
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EXISTS (subquery) |
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An exists_predicate is used to indicate a subquery and then check whether it returns anything. This is done by passing the EXISTS keyword followed by the subquery.
This example returns the total sales when there is a store in the region specified:
SELECT SUM (Sales)
FROM Store_Information
WHERE EXISTS
(SELECT * FROM Geography
WHERE region_name = 'West')
Siehe auch
EIGENSCHAFTEN
Produkt: 4D
Thema: Syntax rules
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4D - SQL Reference ( 4D v19)
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