Document any_value_fallback()

https://github.com/friendica/friendica/pull/3323#discussion_r111663767

diff --git a/include/dba.php b/include/dba.php
index 665580124d895685cfebfe3c9c9616fa2599f25a..4352cde6692fb41a7889e8082f1ff1db090cbc81 100644 (file)
--- a/include/dba.php
+++ b/include/dba.php
@@ -507,12 +507,20 @@ function dbesc($str) {
        }
 }
 
+/**
+ * @brief Replaces ANY_VALUE() function by MIN() function,
+ *  if the database server does not support ANY_VALUE().
+ *
+ * Considerations for Standard SQL, or MySQL with ONLY_FULL_GROUP_BY (default since 5.7.5).
+ * ANY_VALUE() is available from MySQL 5.7.5 https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html
+ * A standard fall-back is to use MIN().
+ *
+ * @param string $sql An SQL string without the values
+ * @return string The input SQL string modified if necessary.
+ */
 function any_value_fallback($sql) {
        global $db;
        $server_info = $db->server_info();
-       //Considerations for Standard SQL, or MySQL with ONLY_FULL_GROUP_BY (default since 5.7.5).
-       //ANY_VALUE() is available from MySQL 5.7.5 https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html
-       //A standard fallback is to use MIN()
        if (version_compare($server_info, '5.7.5', '<') ||
                (stripos($server_info, 'MariaDB') !== false)) {
                $sql = str_ireplace('ANY_VALUE(', 'MIN(', $sql);