SQL check for existence of table values?

Question

SQL

Good time sotok, I have two tables, one with dates, the second with IDs and dates, both tables are presented as a selection by the SELECT statement from child tables, and the first one was created using a CTE expression, I need to check for a match between the values ​​of each element from table 2 in the presence of such a value in the elements of table 1, and in case of a match, increase the date values ​​\u200b\u200b(add a day) in this query and display it (do not change anything in tables with inserts) and additions can be recursive, since after adding a day, you will need to check for availability, tell me how it is most convenient to do this?

Answer 1

most sql databases allow you to use the result of the select operation as a table in from (or define such tables).
about adding a day, the LEFT JOIN operator allows you to join tables in from in such a way that the records of the left table will be required as a result, when as records from the right only if the condition matches ON (similarly, there is a RIGHT JOIN, only the count will be for the right table),
respectively, you check the necessary field on null you do plus one
about recursive additions did not understand