DatabaseCondition::isNull in includes/database/query.inc

Implements QueryConditionInterface::isNull().

DeleteQuery::isNull in includes/database/query.inc

Implements QueryConditionInterface::isNull().

MergeQuery::isNull in includes/database/query.inc

Implements QueryConditionInterface::isNull().

SelectQueryExtender::isNull in includes/database/select.inc

Sets a condition that the specified field be NULL.

SelectQuery::isNull in includes/database/select.inc

Implements QueryConditionInterface::isNull().

UpdateQuery::isNull in includes/database/query.inc

Implements QueryConditionInterface::isNull().