Enable foreign_keys for SQLite. Add unique location id to records.

lib/Database/SQLite.php

@@ -10,6 +10,7 @@ class SQLite extends AbstractDatabase
     {
         $this->db = new \PDO('sqlite:' . $db);
         $this->prefix = '';
+        $this->execute('PRAGMA foreign_keys = ON;');
     }
 
     protected function query(string $sql, array $params = array()): array

sql/schema_mysql.sql

@@ -1,4 +1,5 @@
 CREATE TABLE `locations` (
+  `lid` int(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,
   `dt` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
   `accuracy` int(11) DEFAULT NULL,
   `altitude` int(11) DEFAULT NULL,

sql/schema_sqlite.sql

@@ -1,6 +1,7 @@
 PRAGMA journal_mode=WAL;
 
 CREATE TABLE "locations" (
+  "lid" INTEGER PRIMARY KEY AUTOINCREMENT,
   "dt" INTEGER NOT NULL DEFAULT CURRENT_TIMESTAMP,
   "accuracy" INTEGER,
   "altitude" INTEGER,