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This function determines whether an instance of a specified entity exists, optionally meeting certain criteria.
Syntax
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EXISTS instances [WHERE condition] |
- instances - Instances to search.
- condition - boolean expression that represents the criterion the instance has to meet.
Return type
- boolean
Examples
Suppose the following data model.
| Person.name | Person.gender | Person.age |
|---|---|---|
| “Kim” | “f” | 23 |
| “Rick” | “m” | 35 |
| “Bob” | “m” | 42 |
| “John” | “m” | 19 |
| “Mary” | “f” | 33 |
EXISTS Person= TRUEEXISTS Person WHERE (Person.age < 18)= FALSEEXISTS Person WHERE (Person.gender = “m” AND Person.age > 35)= TRUE
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The return value of a boolean can be |
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EACH
This function determines whether all instances of a specified entity meet a certain criteria
Syntax
| Code Block |
|---|
EACH instances WHERE condition |
- instances - A collection of instances to search.
- condition - Boolean expression that represents the criterion the instance has to meet.
Return type
- boolean
Examples
Suppose the following data model.
| Person.name | Person.gender | Person.age |
|---|---|---|
| “Kim” | “f” | 23 |
| “Rick” | “m” | 35 |
| “Bob” | “m” | 42 |
| “John” | “m” | 19 |
| “Mary” | “f” | 33 |
EACH Person WHERE (Person.age < 18)= FALSEEACH Person WHERE (Person.age > 18)= TRUEEACH Person WHERE (Person.age < 20)= FALSEEACH Person WHERE (Person.gender = “m” OR Person.age > 35)= FALSEEACH Person WHERE (Person.gender = “m” OR Person.age > 20)= TRUE
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