xTuple Connect Guide

Many MetaSQL statements are written to behave in special ways if specific parameters are active or not. For example, many screens let you choose to see Items with all Class Codes, just some Class Codes, or a particular Class Code. These work by having queries that check whether certain MetaSQL parameters are active or not:

SELECT ...
FROM item, ...
WHERE ...
<? if exists("classcode_id") ?>
  AND  (item_classcode_id=<? value("classcode_id") ?>)
<? elseif exists("classcode_pattern") ?>
  AND  (item_classcode_id IN (SELECT classcode_id
                             FROM classcode
                             WHERE (classcode_code ~ <? value("classcode_pattern") ?>)))
<? endif ?>
...

In this example, when the user selects a particular Class Code, the screen makes the classcode_id parameter active. The query then looks only at items with the selected Class Code. If the user enters a Pattern, then the screen makes the classcode_pattern parameter active and all Items with Class Codes matching that pattern are displayed. If neither classcode_id nor classcode_pattern is active, there is no comparison with any Class Code and so all Class Codes are displayed.

If you are not going to make a MetaSQL Parameter active, you do not need to set the type or value for it before submitting the MetaSQL Statement to the xTuple Connect Batch Manager.