选择尚未在Mysql之前查询的记录

Question

How can I retrieve only records that haven't been queried before?

For example:

If I have 3 record in my table:

• Record 1
• Record 2
• Record 3

And I make a query like

`SELECT * FROM TABLE` 

I will get the three record above. If I inserted three more records and I make the query again I just want to see:

• Record 4
• Record 5
• Record 6

Is there a way to make this possible?

Thank you!

Answer 1

A reliable approach is adding some sort of flag to the table that indicates whether the row has been "read" before, and query as follows:

START TRANSACTION;

SELECT * FROM my_table WHERE read_flag = 0 FOR UPDATE;

UPDATE my_table SET read_flag = 1 WHERE id = my_table.id;

COMMIT;

Note that this requires the InnoDB engine.

Answer 2

Which programming langauge are u using?

You could save the id of "Record3", and then query:

select * from table where id > (id_from_record_3)