View source for XA (TQL)

The 'XA' clause value is a variation on the [[X (TQL)|'X']] clause value. The characters 'XA' should be followed by an underscore and the name of an [[Attribute]]; for example '''XA_MONUMENTAL'''.

The result of using 'XA' 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 specified attribute.

Internally, the resulting TQL statements are placed in a single array; Similarly the result will be an array of TQL results.

==Example==
Consider the following (simplified) Building data of a project:
<pre>
[ 
 { "id" : 0, "name" : "Lindelaan 3", "attributes": { "MONUMENTAL" : [0.0], "MEASURED_M2" : [200.0] } },
 { "id" : 1, "name" : "Kerklaan 40", "attributes": { "MONUMENTAL" : [1.0] } }, 
 { "id" : 2, "name" : "Achterweg 7", "attributes": { "MONUMENTAL" : [-3.5] } }, 
 { "id" : 3, "name" : "Achterweg 9", "attributes": { },
 { "id" : 4, "name" : "Kerklaan 61", "attributes": { "MONUMENTAL" : [2.0]} 
 { "id" : 5, "name" : "Duiker 1235", "attributes": { "CULVERT_DIAMETER" : [1.0]},
]
</pre>

The TQL statement to obtain the names of the monumental Buildings is:
<pre>SELECT_NAME_WHERE_BUILDING_IS_XA_MONUMENTAL</pre> 
which internally is replaced with a list of TQL statements, separated by a comma:
<pre>SELECT_NAME_WHERE_BUILDING_IS_1, SELECT_NAME_WHERE_BUILDING_IS_2, SELECT_NAME_WHERE_BUILDING_IS_4</pre>
Its result will be a list of names, separated by comma's:
<pre>"Kerklaan 40", "Achterweg 7", "Kerklaan 61"</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_XA_MONUMENTAL_AND_NAME_IS_MONUMENTAL</pre> 
Its result will be a list of values, separated by a comma:
<pre>1.0, -3.5, 2.0</pre>

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

{{article end
|notes=*The following variants on XA exist:
**XCA: A combination between [[XC (TQL)|XC]] and [[XA (TQL)|XA]].
|seealso=
*[[YA (TQL)]]
*[[X (TQL)]]
*[[XK (TQL)]]
*[[XC (TQL)]]

}}


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