COUNT
Retrieves the number of instances for the specified entities or attributes. Please note the similar function SIZE.
Syntax
COUNT ( collection ) |
Input
- collection - A collection of attribute or entity instances.
Return type
- integer
Examples
Suppose the following data model.
| Instance | Person.name |
|---|---|
| 1 | “John” |
| 2 | “Dave” |
| 3 | “Jane” |
| 4 | “Lisa” |
| Instance | House.rooms |
|---|---|
| singleton | “living room”, “bathroom”, “bedroom” |
| Expression | Result | Type |
|---|---|---|
| COUNT ( ALL Person ) | 4 | Integer |
| COUNT ( House.rooms ) | 3 | Integer |
| COUNT ( ALL Person + ALL House ) | 5 | Integer |
| COUNT ( COLLECT Person FROM ALL Person WHERE ( Person.name = “Lisa” ) ) | 1 | Integer |
| COUNT ( ? (= UNKNOWN) ) | UNKNOWN | Integer |