Adds a tag to a query.
Tags are strings that identify a query. A query may have any number of tags. Tags are used to mark a query so that alter hooks may decide if they wish to take action. Tags should be all lower-case and contain only letters, numbers, and underscore, and start with a letter. That is, they should follow the same rules as PHP identifiers in general.
$tag: The tag to add.
QueryAlterableInterface: The called object.
includes/ database/ select.inc, line 589
- The base extender class for Select queries.