+ * Merges the provided conditions into a single collapsed one
+ *
+ * @param array ...$conditions One or more condition arrays
+ * @return array A collapsed condition
+ * @see DBA::collapseCondition() for the condition array formats
+ */
+ public static function mergeConditions(array ...$conditions)
+ {
+ if (count($conditions) == 1) {
+ return current($conditions);
+ }
+
+ $conditionStrings = [];
+ $result = [];
+
+ foreach ($conditions as $key => $condition) {
+ if (!$condition) {
+ continue;
+ }
+
+ $condition = self::collapseCondition($condition);
+
+ $conditionStrings[] = array_shift($condition);
+ // The result array holds the eventual parameter values
+ $result = array_merge($result, $condition);
+ }
+
+ if (count($conditionStrings)) {
+ // We prepend the condition string at the end to form a collapsed condition array again
+ array_unshift($result, implode(' AND ', $conditionStrings));
+ }
+
+ return $result;
+ }
+
+ /**
+ * Returns the SQL parameter string built from the provided parameter array
+ *
+ * Expected format for each key:
+ *
+ * group_by:
+ * - list of column names
+ *
+ * order:
+ * - numeric keyed column name => ASC
+ * - associative element with boolean value => DESC (true), ASC (false)
+ * - associative element with string value => 'ASC' or 'DESC' literally
+ *
+ * limit:
+ * - single numeric value => count
+ * - list with two numeric values => offset, count