sql - How to truncate and add new rows to the table with a select query never getting empty results -

I have a requirement where a table holds the position of some things. This table has been shortened and new position data entered in every second. The problem is that if a selected query is executed and executed between the following inputs, then the blank table will change to the user. SQL transactions will not help me here, but not sure. Also, if the query between the query is removed and inserted, then it should not return the error because it is blocked by a database lock. It should just wait + until the process of converge ends.

What would be the best way to implement such a system? How do I create a "Delete + Insert" query and "Selection" query?

Thank you in advance.

-------- Additional information This table should be the result of a lot of heavy questions and each other will be updated so that the application does not run those heavy questions and instead, Will get the required information from Then put a small piece and each other and multiple selection at random.

Do not skip the table. Instead, enter the new position using the date as the primary key or primary key. Repeat:

  from date of the date to date 19th, <1> select date at the top  

or

  Max select  

from the table. (These should be basically the same execution plan.)

Then, you enter a new date. When inserted, the data is immediately available.

Then you can delete large rows in your holiday.