View source for YK (TQL)

The 'YK' clause value is a variation on the [[YA (TQL)|'YA']] clause value. The characters 'YK' should be followed by an underscore and the name of a [[Key]]; for example '''YK_CULVERT_DIAMETER'''. Also see the [[#Example|example ]]below. 

This Key is used to obtain the name of an Attribute, given a Grid Overlay. This Grid Overlay is obtained from the same TQL statement, which should contain one of the following clause parameters: 
* [[Grid (TQL Param)]]
* [[Grid with attribute (TQL Param)]] 
* [[Gridtype (TQL Param)]]

The result of using 'YK' for the clause value, is the automatic creation of multiple TQL statements, one with each Item ID for that Clause Parameter that can be found in the project data. Items are only taken into account of they have a non-zero value for the attribute specified by the Grid Overlay [[Key]].

Internally, the resulting TQL statements are placed an array of arrays; Similarly the result will be an array of TQL result arrays.

==Example==
Consider the following (simplified) Building data of a project:
<pre>
[ 
 { "id" : 0, "name" : "Duiker A", "attributes": { "CULVERT_DIAMETER" : [1.0], "MEASURED_DIAM" : [0.2] } },
 { "id" : 1, "name" : "Kerklaan", "attributes": { "MONUMENTAL_HOUSE" : [1.0] } }, 
 { "id" : 2, "name" : "Duiker B", "attributes": { "CULVERT_DIAMETER" : [0.5], "MEASURED_DIAM" : [1.0], } }, 
 { "id" : 3, "name" : "Duiker C", "attributes": { "CULVERT_DIAMETER" : [1.0] } },
 { "id" : 4, "name" : "Duiker K", "attributes": { "CULVERT_DIAMETER" : [2.0], "MEASURED_DIAM" : [0.0] } } 
 { "id" : 5, "name" : "Duiker M", "attributes": { "CULVERT_DIAMETER" : [0.0], "MEASURED_DIAM" : [2.0] } },
]
</pre>

And the Grid Overlay in the same project:
<pre>{ "id" : 6, "name" : "Water Overlay", "type" : "RAINFALL" , "keys": { "CULVERT_DIAMETER" : "MEASURED_DIAM" } }</pre>

The TQL statement to obtain the names of the Culverts used by the Water Overlay is:
<pre>SELECT_NAME_WHERE_BUILDING_IS_YK_CULVERT_DIAMETER_AND_GRID_IS_6</pre> 
which internally is replaced with a list of TQL statements, separated by comma's,
<pre>SELECT_NAME_WHERE_BUILDING_IS_0_AND_GRID_IS_6, SELECT_NAME_WHERE_BUILDING_IS_2_AND_GRID_IS_6, SELECT_NAME_WHERE_BUILDING_IS_5_AND_GRID_IS_6</pre>
Its result will be a list of arrays of names, separated by a comma:
<pre>["Duiker A"], ["Duiker B"], ["Duiker M"]</pre>
Similarly, the TQL statement to obtain the culvert Diameters of the Culverts used by the water Overlay is:
<pre>SELECT_ATTRIBUTE_WHERE_BUILDING_IS_YK_CULVERT_DIAMETER_AND_GRID_IS_6_AND_KEY_IS_CULVERT_DIAMETER</pre> 
Its result will be a list of arrays of values, separated by a comma:
<pre>[0.2], [1.0], [2.0]</pre>

==Clause Parameters==
The YK value can be used in the following TQL Clause parameters:

{{article end
|notes=*In case no Grid is specified by any of the other clauses of the original TQL statement, the result will be 0 generated TQL statements; an empty array.
|seealso=
*[[XK (TQL)]]
*[[Y (TQL)]]
*[[YA (TQL)]]
*[[YC (TQL)]]

}}


{{TQL param nav}}