Avg_Row_length没有显示任何结果

Question

我试图在PHP中获取Avg_Row_length但是当我回显结果时它什么都没显示。我试图调试该问题，但没有创建日志。

我的查询：

$avg_length_row = mysqli_query($con, "SELECT Avg_Row_length FROM 'information_schema.tables' WHERE table_name = 'assignment'");
echo "AVG LENGTH " . (string)$avg_length_row . "<br>";