Sudoku Lösungstechnik '/solving.php/technic/Hidden

Fatal error: Uncaught mysqli_sql_exception: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''' at line 1 in /mnt/web513/b3/63/51663363/htdocs/ahr-software/sudoku/solving.php:106 Stack trace: #0 /mnt/web513/b3/63/51663363/htdocs/ahr-software/sudoku/solving.php(106): mysqli->query('SELECT s1.id, s...') #1 {main} thrown in /mnt/web513/b3/63/51663363/htdocs/ahr-software/sudoku/solving.php on line 106