要查询表中不存在的数据，可以使用子查询或者联合查询来实现。以下是一些示例：
SELECT column_name
FROM table_name
WHERE column_name NOT IN (SELECT distinct_column_name FROM another_table);
SELECT t1.column_name
FROM table1 t1
LEFT JOIN table2 t2 ON t1.column_name = t2.column_name
WHERE t2.column_name IS NULL;
SELECT column_name
FROM table_name t1
WHERE NOT EXISTS (SELECT 1 FROM another_table t2 WHERE t1.column_name = t2.column_name);
根据具体情况选择合适的方法来查询表中不存在的数据。
