Select_data
Relational functions select_data
- select_data(domain unit, condition, attribute)
The select_data(domain unit, condition, attribute) function results relates the attribute argument to the domain unit argument, based on the condition argument.
The select_data is mostly used together with the select_many function.
- unit domain unit with value type uint32
- condition must be a boolean attribute or subexpression resulting in boolean values.
- attribute: an attribute that must have matching value type and metric with the resulting attribute.
7.305
unit<uint32> ZHCities := select_many(City, City/RegionCode == 200)
{
attribute<string> name :=
select_data(., City/RegionCode == 200, CityLabels/Name);
}
| City/RegionCode | City/Name |
|---|---|
| 100 | Amsterdam |
| 200 | Rotterdam |
| 300 | Utrecht |
| 200 | Den Haag |
| 400 | Eindhoven |
| null | Haarlem |
| 400 | Tilburg |
domain City, nr of rows = 7
| ZHCities/name |
|---|
| Rotterdam |
| Den Haag |
domain ZHCities, nr of rows = 2
