DatabaseBase: Document behavior of nulls in array conditions

Follows-up 26235c73376b.

Change-Id: Id008557e53a8c27f49e87cb2120298ce6478b6df

diff --git a/includes/db/Database.php b/includes/db/Database.php
index 8ce7f3f..0a2e221 100644 (file)
--- a/includes/db/Database.php
+++ b/includes/db/Database.php
@@ -1638,9 +1638,10 @@ abstract class DatabaseBase implements IDatabase {
         *     - If the value of such an array element is a scalar (such as a
         *       string), it will be treated as data and thus quoted appropriately.
         *       If it is null, an IS NULL clause will be added.
-        *     - If the value is an array, an IN(...) clause will be constructed,
-        *       such that the field name may match any of the elements in the
-        *       array. The elements of the array will be quoted.
+        *     - If the value is an array, an IN (...) clause will be constructed
+        *       from its non-null elements, and an IS NULL clause will be added
+        *       if null is present, such that the field may match any of the
+        *       elements in the array. The non-null elements will be quoted.
         *
         * Note that expressions are often DBMS-dependent in their syntax.
         * DBMS-independent wrappers are provided for constructing several types of